diff --git a/.codecov.yml b/.codecov.yml
index 7072c0262cbf..95023199dd73 100644
--- a/.codecov.yml
+++ b/.codecov.yml
@@ -5,9 +5,9 @@ codecov:
   ci:
     - 'travis.org'
   max_report_age: 24
-  require_ci_to_pass: yes
+  require_ci_to_pass: no
   notify:
-    wait_for_ci: yes
+    wait_for_ci: no
 
 # Pull request comments disabled because they were too noisy
 # See https://docs.codecov.io/docs/pull-request-comments
@@ -18,19 +18,19 @@ comment: false
 coverage:
   precision: 2
   round: down
-  range: '80...100'
+  range: '75...100'
   status:
     project:
       default:
         base: auto
         if_not_found: success
         only_pulls: true
-        target: 80%
+        target: 75%
         threshold: 1%
     patch:
       default:
         base: auto
         if_not_found: success
         only_pulls: true
-        target: 80%
+        target: 75%
         threshold: 1%
diff --git a/3p/twitter.js b/3p/twitter.js
index 59357add44eb..7bc39f784e60 100644
--- a/3p/twitter.js
+++ b/3p/twitter.js
@@ -97,12 +97,12 @@ export function twitter(global, data) {
       return;
     }
 
-    resize(el);
+    resize(/** @type {!Element} */ (el));
     twttr.events.bind('resize', (event) => {
       // To be safe, make sure the resize event was triggered for the widget we
       // created below.
       if (el === event.target) {
-        resize(el);
+        resize(/** @type {!Element} */ (el));
       }
     });
   }
diff --git a/ads/inabox/inabox-host.md b/ads/inabox/inabox-host.md
index 0adfe8bdffe9..24f950c3e633 100644
--- a/ads/inabox/inabox-host.md
+++ b/ads/inabox/inabox-host.md
@@ -78,11 +78,6 @@ Main workflow:
 1. The ads tag creates an iframe, and set the response content
    to the iframe using `srcdoc`.
 
-Note that this friendly iframe approach right now is in an experimental
-stage. Put the following meta tag in the head of the ad HTML to opt-in
-the experiment:
-`<meta name="amp-experiments-opt-in" content="inabox-viewport-friendly">`.
-
 ###### Security assurance
 
 In case that the AMPHTML ad is generated by a 3rd party, to ensure it's
diff --git a/build-system/common/utils.js b/build-system/common/utils.js
index 3b1f80ed4ccb..3c945f860f52 100644
--- a/build-system/common/utils.js
+++ b/build-system/common/utils.js
@@ -29,10 +29,22 @@ const ROOT_DIR = path.resolve(__dirname, '../../');
 /**
  * Cleans and builds binaries with --fortesting flag and
  * overriden config.
+ *
+ * @param {boolean} minified
  */
-function buildMinifiedRuntime() {
+// TODO(gh/amphtml/28312): Directly call dist() or build()
+// instead of spwaning a new process.
+function buildRuntime(minified = true) {
   execOrDie('gulp clean');
-  execOrDie(`gulp dist --fortesting --config ${argv.config}`);
+
+  let command = minified ? `gulp dist --fortesting` : `gulp build --fortesting`;
+  if (argv.core_runtime_only) {
+    command += ` --core_runtime_only`;
+  } else if (argv.extensions) {
+    command += ` --extensions=${argv.extensions}`;
+  }
+
+  execOrDie(command);
 }
 
 /**
@@ -157,7 +169,7 @@ function installPackages(dir) {
 }
 
 module.exports = {
-  buildMinifiedRuntime,
+  buildRuntime,
   getFilesChanged,
   getFilesFromArgv,
   getFilesToCheck,
diff --git a/build-system/compile/compile.js b/build-system/compile/compile.js
index 6123fd11cd7e..8318a8ef3a23 100644
--- a/build-system/compile/compile.js
+++ b/build-system/compile/compile.js
@@ -266,7 +266,7 @@ function compile(
       compilation_level: options.compilationLevel || 'SIMPLE_OPTIMIZATIONS',
       // Turns on more optimizations.
       assume_function_wrapper: true,
-      language_in: 'ECMASCRIPT_2018',
+      language_in: 'ECMASCRIPT_2020',
       // Do not transpile down to ES5 if running with `--esm`, since we do
       // limited transpilation in Babel.
       language_out: argv.esm ? 'NO_TRANSPILE' : 'ECMASCRIPT5',
diff --git a/build-system/compile/single-pass.js b/build-system/compile/single-pass.js
index 5dd692b623fe..43579fd53be6 100644
--- a/build-system/compile/single-pass.js
+++ b/build-system/compile/single-pass.js
@@ -107,7 +107,7 @@ exports.getFlags = function (config) {
     // accessing the symbol, we remedy this by attaching all public exports
     // to `_` and everything imported across modules is is accessed through `_`.
     rename_prefix_namespace: '_',
-    language_in: 'ECMASCRIPT_2018',
+    language_in: 'ECMASCRIPT_2020',
     language_out: config.esm
       ? 'NO_TRANSPILE'
       : config.language_out || 'ECMASCRIPT5',
diff --git a/build-system/global-configs/canary-config.json b/build-system/global-configs/canary-config.json
index 202b4e78e626..b99c28447964 100644
--- a/build-system/global-configs/canary-config.json
+++ b/build-system/global-configs/canary-config.json
@@ -1,9 +1,5 @@
 {
-  "allow-doc-opt-in": [
-    "amp-next-page",
-    "inabox-viewport-friendly",
-    "analytics-chunks"
-  ],
+  "allow-doc-opt-in": ["amp-next-page", "analytics-chunks"],
   "allow-url-opt-in": ["pump-early-frame"],
   "canary": 1,
   "a4aProfilingRate": 0.01,
diff --git a/build-system/global-configs/experiments-config.json b/build-system/global-configs/experiments-config.json
index 6aff5ed333c9..8f0b87d0f3fb 100644
--- a/build-system/global-configs/experiments-config.json
+++ b/build-system/global-configs/experiments-config.json
@@ -7,13 +7,6 @@
     "expirationDateUTC": "2020-05-31",
     "defineExperimentConstant": "INTERSECTION_OBSERVER_POLYFILL"
   },
-  "experimentB": {
-    "name": "MOVE_FIXED_LAYER",
-    "environment": "AMP",
-    "command": "gulp dist --define_experiment_constant=MOVE_FIXED_LAYER",
-    "issue": "",
-    "expiration_date_utc": "2020-12-31",
-    "define_experiment_constant": "MOVE_FIXED_LAYER"
-  },
+  "experimentB": {},
   "experimentC": {}
 }
diff --git a/build-system/global-configs/prod-config.json b/build-system/global-configs/prod-config.json
index c4d5bde7575d..82ac5779df95 100644
--- a/build-system/global-configs/prod-config.json
+++ b/build-system/global-configs/prod-config.json
@@ -1,9 +1,5 @@
 {
-  "allow-doc-opt-in": [
-    "amp-next-page",
-    "inabox-viewport-friendly",
-    "analytics-chunks"
-  ],
+  "allow-doc-opt-in": ["amp-next-page", "analytics-chunks"],
   "allow-url-opt-in": ["pump-early-frame"],
   "canary": 0,
   "a4aProfilingRate": 0.01,
@@ -37,5 +33,7 @@
   "random-subdomain-for-safeframe": 0.02,
   "swg-gpay-api": 1,
   "swg-gpay-native": 1,
-  "version-locking": 1
+  "version-locking": 1,
+  "amp-ad-no-center-css": 0.05,
+  "analytics-chunks": 1
 }
diff --git a/build-system/pr-check/OWNERS b/build-system/pr-check/OWNERS
index 2c8f163b1f3d..8425845cae3e 100644
--- a/build-system/pr-check/OWNERS
+++ b/build-system/pr-check/OWNERS
@@ -4,11 +4,7 @@
 {
   rules: [
     {
-      owners: [
-        {name: 'ampproject/wg-infra'},
-        {name: 'estherkim', notify: true},
-        {name: 'rsimha', notify: true},
-      ],
+      owners: [{name: 'ampproject/wg-infra'}, {name: 'rsimha', notify: true}],
     },
   ],
 }
diff --git a/build-system/pr-check/build-targets.js b/build-system/pr-check/build-targets.js
index 89397fb17121..38b4cfee3723 100644
--- a/build-system/pr-check/build-targets.js
+++ b/build-system/pr-check/build-targets.js
@@ -147,6 +147,12 @@ const targetMatchers = {
   'PACKAGE_UPGRADE': (file) => {
     return file == 'package.json' || file == 'yarn.lock';
   },
+  'RUNTIME': (file) => {
+    if (isOwnersFile(file)) {
+      return false;
+    }
+    return file.startsWith('src/');
+  },
   'SERVER': (file) => {
     if (isOwnersFile(file)) {
       return false;
diff --git a/build-system/pr-check/e2e-tests.js b/build-system/pr-check/e2e-tests.js
index 62f37da13196..5b34a16d80bf 100644
--- a/build-system/pr-check/e2e-tests.js
+++ b/build-system/pr-check/e2e-tests.js
@@ -42,7 +42,7 @@ async function main() {
   if (!isTravisPullRequestBuild()) {
     downloadDistOutput(FILENAME);
     timedExecOrDie('gulp update-packages');
-    timedExecOrDie('gulp e2e --nobuild --headless');
+    timedExecOrDie('gulp e2e --nobuild --headless --compiled');
   } else {
     printChangeSummary(FILENAME);
     const buildTargets = determineBuildTargets(FILENAME);
@@ -53,7 +53,7 @@ async function main() {
     ) {
       downloadDistOutput(FILENAME);
       timedExecOrDie('gulp update-packages');
-      timedExecOrDie('gulp e2e --nobuild --headless');
+      timedExecOrDie('gulp e2e --nobuild --headless --compiled');
     } else {
       console.log(
         `${FILELOGPREFIX} Skipping`,
diff --git a/build-system/pr-check/experiment-tests.js b/build-system/pr-check/experiment-tests.js
index ae62530b53c9..bd39d39cbcda 100644
--- a/build-system/pr-check/experiment-tests.js
+++ b/build-system/pr-check/experiment-tests.js
@@ -60,7 +60,7 @@ function build_(config) {
 
 function test_() {
   timedExecOrDie('gulp integration --nobuild --compiled --headless');
-  timedExecOrDie('gulp e2e --nobuild --headless');
+  timedExecOrDie('gulp e2e --nobuild --compiled --headless');
 }
 
 function main() {
diff --git a/build-system/server/routes/a4a-envelopes.js b/build-system/server/routes/a4a-envelopes.js
index 1247b611f63b..0912d7329845 100644
--- a/build-system/server/routes/a4a-envelopes.js
+++ b/build-system/server/routes/a4a-envelopes.js
@@ -48,14 +48,12 @@ app.use('/inabox-(friendly|safeframe)', (req, res) => {
   fs.promises
     .readFile(process.cwd() + templatePath, 'utf8')
     .then((template) => {
-      let url;
+      const url = getInaboxUrl(req);
       if (req.baseUrl == '/inabox-friendly') {
-        url = getInaboxUrl(req, 'inabox-viewport-friendly');
         template = template
           .replace('SRCDOC_ATTRIBUTE', 'srcdoc="BODY"')
           .replace('INABOX_ADS_TAG_INTEGRATION', '');
       } else {
-        url = getInaboxUrl(req);
         template = template
           .replace(
             /NAME/g,
diff --git a/build-system/tasks/e2e/functional-test-controller.js b/build-system/tasks/e2e/functional-test-controller.js
index 6e19f8dd74f7..934e21081d4f 100644
--- a/build-system/tasks/e2e/functional-test-controller.js
+++ b/build-system/tasks/e2e/functional-test-controller.js
@@ -170,9 +170,10 @@ class FunctionalTestController {
    * {@link https://www.w3.org/TR/webdriver1/#find-element}
    *
    * @param {string} unusedSelector
+   * @param {number=} unusedTimeout
    * @return {!Promise<!ElementHandle>}
    */
-  async findElement(unusedSelector) {}
+  async findElement(unusedSelector, unusedTimeout) {}
 
   /**
    * The Find Elements command is used to find all elements matching the
diff --git a/build-system/tasks/e2e/index.js b/build-system/tasks/e2e/index.js
index f525ee226ad9..94c15868914d 100644
--- a/build-system/tasks/e2e/index.js
+++ b/build-system/tasks/e2e/index.js
@@ -24,7 +24,7 @@ const log = require('fancy-log');
 const Mocha = require('mocha');
 const path = require('path');
 const {
-  buildMinifiedRuntime,
+  buildRuntime,
   getFilesFromArgv,
   installPackages,
 } = require('../../common/utils');
@@ -39,11 +39,11 @@ const PORT = 8000;
 const SLOW_TEST_THRESHOLD_MS = 2500;
 const TEST_RETRIES = isTravisBuild() ? 2 : 0;
 
-async function launchWebServer_() {
+async function launchWebServer_(minified) {
   await startServer(
     {host: HOST, port: PORT},
     {quiet: !argv.debug},
-    {compiled: true}
+    {compiled: minified}
   );
 }
 
@@ -84,11 +84,11 @@ async function e2e() {
 
   // build runtime
   if (!argv.nobuild) {
-    buildMinifiedRuntime();
+    buildRuntime(/* minified */ !!argv.compiled);
   }
 
   // start up web server
-  await launchWebServer_();
+  await launchWebServer_(/* minified */ argv.compiled);
 
   // run tests
   if (!argv.watch) {
@@ -150,7 +150,11 @@ e2e.flags = {
     '`chrome`, `firefox`, `safari`.',
   'config':
     '  Sets the runtime\'s AMP_CONFIG to one of "prod" (default) or "canary"',
-  'nobuild': '  Skips building the runtime via `gulp dist --fortesting`',
+  'core_runtime_only': '  Builds only the core runtime.',
+  'nobuild':
+    '  Skips building the runtime via `gulp (build|dist) --fortesting`',
+  'extensions': '  Builds only the listed extensions.',
+  'compiled': '  Runs the tests using minified js',
   'files': '  Run tests found in a specific path (ex: **/test-e2e/*.js)',
   'testnames': '  Lists the name of each test being run',
   'watch': '  Watches for changes in files, runs corresponding test(s)',
diff --git a/build-system/tasks/e2e/package.json b/build-system/tasks/e2e/package.json
index 9ece0207a85f..4753a2633edf 100644
--- a/build-system/tasks/e2e/package.json
+++ b/build-system/tasks/e2e/package.json
@@ -7,7 +7,7 @@
     "@babel/register": "7.9.0",
     "babel-regenerator-runtime": "6.5.0",
     "chromedriver": "81.0.0",
-    "puppeteer": "3.0.2",
+    "puppeteer": "3.0.4",
     "geckodriver": "1.19.1",
     "selenium-webdriver": "4.0.0-alpha.7"
   },
diff --git a/build-system/tasks/e2e/puppeteer-controller.js b/build-system/tasks/e2e/puppeteer-controller.js
index a9f8269006fc..263ac2868e48 100644
--- a/build-system/tasks/e2e/puppeteer-controller.js
+++ b/build-system/tasks/e2e/puppeteer-controller.js
@@ -189,17 +189,18 @@ class PuppeteerController {
 
   /**
    * @param {string} selector
+   * @param {number=} timeout
    * @return {!Promise<!ElementHandle<!PuppeteerHandle>>}
    * @override
    */
-  async findElement(selector) {
+  async findElement(selector, timeout = DEFAULT_WAIT_TIMEOUT) {
     const frame = await this.getCurrentFrame_();
     const root = await this.getRoot_();
     const jsHandle = await frame.waitForFunction(
       (root, selector) => {
         return root./*OK*/ querySelector(selector);
       },
-      {timeout: DEFAULT_WAIT_TIMEOUT},
+      {timeout},
       root,
       selector
     );
diff --git a/build-system/tasks/e2e/selenium-webdriver-controller.js b/build-system/tasks/e2e/selenium-webdriver-controller.js
index ea57e7343dbb..ae55755ded7a 100644
--- a/build-system/tasks/e2e/selenium-webdriver-controller.js
+++ b/build-system/tasks/e2e/selenium-webdriver-controller.js
@@ -117,10 +117,11 @@ class SeleniumWebDriverController {
    * until.js#elementLocated
    * {@link https://github.com/SeleniumHQ/selenium/blob/6a717f20/javascript/node/selenium-webdriver/lib/until.js#L237}
    * @param {string} selector
+   * @param {number=} timeout
    * @return {!Promise<!ElementHandle<!WebElement>>}
    * @override
    */
-  async findElement(selector) {
+  async findElement(selector, timeout = ELEMENT_WAIT_TIMEOUT) {
     const bySelector = By.css(selector);
 
     const label = 'for element to be located ' + selector;
@@ -139,7 +140,7 @@ class SeleniumWebDriverController {
         throw e;
       }
     });
-    const webElement = await this.driver.wait(condition, ELEMENT_WAIT_TIMEOUT);
+    const webElement = await this.driver.wait(condition, timeout);
     return new ElementHandle(webElement, this);
   }
 
diff --git a/build-system/tasks/e2e/yarn.lock b/build-system/tasks/e2e/yarn.lock
index 7acdf01bc912..09eed59681a5 100644
--- a/build-system/tasks/e2e/yarn.lock
+++ b/build-system/tasks/e2e/yarn.lock
@@ -53,11 +53,6 @@
     "@types/minimatch" "*"
     "@types/node" "*"
 
-"@types/mime-types@^2.1.0":
-  version "2.1.0"
-  resolved "https://registry.yarnpkg.com/@types/mime-types/-/mime-types-2.1.0.tgz#9ca52cda363f699c69466c2a6ccdaad913ea7a73"
-  integrity sha1-nKUs2jY/aZxpRmwqbM2q2RPqenM=
-
 "@types/minimatch@*":
   version "3.0.3"
   resolved "https://registry.yarnpkg.com/@types/minimatch/-/minimatch-3.0.3.tgz#3dca0e3f33b200fc7d1139c0cd96c1268cadfd9d"
@@ -662,18 +657,6 @@ micromatch@^4.0.2:
     braces "^3.0.1"
     picomatch "^2.0.5"
 
-mime-db@1.43.0:
-  version "1.43.0"
-  resolved "https://registry.yarnpkg.com/mime-db/-/mime-db-1.43.0.tgz#0a12e0502650e473d735535050e7c8f4eb4fae58"
-  integrity sha512-+5dsGEEovYbT8UY9yD7eE4XTc4UwJ1jBYlgaQQF38ENsKR3wj/8q8RFZrF9WIZpB2V1ArTVFUva8sAul1NzRzQ==
-
-mime-types@^2.1.25:
-  version "2.1.26"
-  resolved "https://registry.yarnpkg.com/mime-types/-/mime-types-2.1.26.tgz#9c921fc09b7e149a65dfdc0da4d20997200b0a06"
-  integrity sha512-01paPWYgLrkqAyrlDorC1uDwl2p3qZT7yl806vW7DvDoxwXi46jsjFbg+WdwotBIk6/MbEhO/dh5aZ5sNj/dWQ==
-  dependencies:
-    mime-db "1.43.0"
-
 mime@^2.0.3:
   version "2.4.0"
   resolved "https://registry.yarnpkg.com/mime/-/mime-2.4.0.tgz#e051fd881358585f3279df333fe694da0bcffdd6"
@@ -882,17 +865,15 @@ pump@^3.0.0:
     end-of-stream "^1.1.0"
     once "^1.3.1"
 
-puppeteer@3.0.2:
-  version "3.0.2"
-  resolved "https://registry.yarnpkg.com/puppeteer/-/puppeteer-3.0.2.tgz#1d08cdb7c0c2666f5e743221b1cb1946fea493f0"
-  integrity sha512-5jS/POFVDW9fqb76O8o0IBpXOnq+Na8ocGMggYtnjCRBRqmAFvX0csmwgLOHkYnQ/vCBcBPYlOq0Pp60z1850Q==
+puppeteer@3.0.4:
+  version "3.0.4"
+  resolved "https://registry.yarnpkg.com/puppeteer/-/puppeteer-3.0.4.tgz#f445aae0a6732c65bbb90e963dcd6fd8fde0d780"
+  integrity sha512-1QEb4tJXXbNId7WSHlcDkS3B4GklTIebKn8Y9D6B7tAdUjQncb+8QlTjbQsAgGX5dhRG32Qycuk5XKzJgLs0sg==
   dependencies:
-    "@types/mime-types" "^2.1.0"
     debug "^4.1.0"
     extract-zip "^2.0.0"
     https-proxy-agent "^4.0.0"
     mime "^2.0.3"
-    mime-types "^2.1.25"
     progress "^2.0.1"
     proxy-from-env "^1.0.0"
     rimraf "^3.0.2"
diff --git a/build-system/tasks/performance/config.json b/build-system/tasks/performance/config.json
index 9474ff1cdd26..791640714400 100644
--- a/build-system/tasks/performance/config.json
+++ b/build-system/tasks/performance/config.json
@@ -9,8 +9,8 @@
     {
       "handlerName": "analyticsHandler",
       "urls": [
-        "http://localhost:8000/test/manual/amp-analytics/performanceTestPages/visible-basic.html",
-        "http://localhost:8000/test/manual/amp-analytics/performanceTestPages/visible-multiple.html"
+        "http://localhost:8000/test/manual/amp-analytics/performance-test-pages/visible-basic.html",
+        "http://localhost:8000/test/manual/amp-analytics/performance-test-pages/visible-multiple.html"
       ],
       "timeout": 2000,
       "extraUrlParam": {
diff --git a/build-system/tasks/performance/package.json b/build-system/tasks/performance/package.json
index 2c2c347de469..487d57ae473a 100644
--- a/build-system/tasks/performance/package.json
+++ b/build-system/tasks/performance/package.json
@@ -6,6 +6,6 @@
   "devDependencies": {
     "chai": "4.2.0",
     "mocha": "7.1.2",
-    "puppeteer": "3.0.2"
+    "puppeteer": "3.0.4"
   }
 }
diff --git a/build-system/tasks/performance/yarn.lock b/build-system/tasks/performance/yarn.lock
index c17efe8a2c6a..7294aa20e9f5 100644
--- a/build-system/tasks/performance/yarn.lock
+++ b/build-system/tasks/performance/yarn.lock
@@ -2,11 +2,6 @@
 # yarn lockfile v1
 
 
-"@types/mime-types@^2.1.0":
-  version "2.1.0"
-  resolved "https://registry.yarnpkg.com/@types/mime-types/-/mime-types-2.1.0.tgz#9ca52cda363f699c69466c2a6ccdaad913ea7a73"
-  integrity sha1-nKUs2jY/aZxpRmwqbM2q2RPqenM=
-
 "@types/node@*":
   version "13.13.2"
   resolved "https://registry.yarnpkg.com/@types/node/-/node-13.13.2.tgz#160d82623610db590a64e8ca81784e11117e5a54"
@@ -537,18 +532,6 @@ log-symbols@3.0.0:
   dependencies:
     chalk "^2.4.2"
 
-mime-db@1.43.0:
-  version "1.43.0"
-  resolved "https://registry.yarnpkg.com/mime-db/-/mime-db-1.43.0.tgz#0a12e0502650e473d735535050e7c8f4eb4fae58"
-  integrity sha512-+5dsGEEovYbT8UY9yD7eE4XTc4UwJ1jBYlgaQQF38ENsKR3wj/8q8RFZrF9WIZpB2V1ArTVFUva8sAul1NzRzQ==
-
-mime-types@^2.1.25:
-  version "2.1.26"
-  resolved "https://registry.yarnpkg.com/mime-types/-/mime-types-2.1.26.tgz#9c921fc09b7e149a65dfdc0da4d20997200b0a06"
-  integrity sha512-01paPWYgLrkqAyrlDorC1uDwl2p3qZT7yl806vW7DvDoxwXi46jsjFbg+WdwotBIk6/MbEhO/dh5aZ5sNj/dWQ==
-  dependencies:
-    mime-db "1.43.0"
-
 mime@^2.0.3:
   version "2.4.4"
   resolved "https://registry.yarnpkg.com/mime/-/mime-2.4.4.tgz#bd7b91135fc6b01cde3e9bae33d659b63d8857e5"
@@ -728,17 +711,15 @@ pump@^3.0.0:
     end-of-stream "^1.1.0"
     once "^1.3.1"
 
-puppeteer@3.0.2:
-  version "3.0.2"
-  resolved "https://registry.yarnpkg.com/puppeteer/-/puppeteer-3.0.2.tgz#1d08cdb7c0c2666f5e743221b1cb1946fea493f0"
-  integrity sha512-5jS/POFVDW9fqb76O8o0IBpXOnq+Na8ocGMggYtnjCRBRqmAFvX0csmwgLOHkYnQ/vCBcBPYlOq0Pp60z1850Q==
+puppeteer@3.0.4:
+  version "3.0.4"
+  resolved "https://registry.yarnpkg.com/puppeteer/-/puppeteer-3.0.4.tgz#f445aae0a6732c65bbb90e963dcd6fd8fde0d780"
+  integrity sha512-1QEb4tJXXbNId7WSHlcDkS3B4GklTIebKn8Y9D6B7tAdUjQncb+8QlTjbQsAgGX5dhRG32Qycuk5XKzJgLs0sg==
   dependencies:
-    "@types/mime-types" "^2.1.0"
     debug "^4.1.0"
     extract-zip "^2.0.0"
     https-proxy-agent "^4.0.0"
     mime "^2.0.3"
-    mime-types "^2.1.25"
     progress "^2.0.1"
     proxy-from-env "^1.0.0"
     rimraf "^3.0.2"
diff --git a/build-system/tasks/presubmit-checks.js b/build-system/tasks/presubmit-checks.js
index 6198cbb51256..4c5d2acf6061 100644
--- a/build-system/tasks/presubmit-checks.js
+++ b/build-system/tasks/presubmit-checks.js
@@ -625,6 +625,7 @@ const forbiddenTerms = {
       'dist.3p/current/integration.js', // Includes the previous.
       'src/polyfills/custom-elements.js',
       'ads/google/imaVideo.js', // Required until #22277 is fixed.
+      '3p/twitter.js', // Runs in a 3p window context, so cannot import log.js.
     ],
   },
   'startupChunk\\(': {
diff --git a/build-system/tasks/runtime-test/OWNERS b/build-system/tasks/runtime-test/OWNERS
index d3a1b00d7fa5..32c5ea6d7543 100644
--- a/build-system/tasks/runtime-test/OWNERS
+++ b/build-system/tasks/runtime-test/OWNERS
@@ -4,10 +4,7 @@
 {
   rules: [
     {
-      owners: [
-        {name: 'ampproject/wg-infra'},
-        {name: 'estherkim', notify: true},
-      ],
+      owners: [{name: 'ampproject/wg-infra'}],
     },
   ],
 }
diff --git a/build-system/tasks/visual-diff/index.js b/build-system/tasks/visual-diff/index.js
index 1d65e4f925bf..8378f9ddda67 100644
--- a/build-system/tasks/visual-diff/index.js
+++ b/build-system/tasks/visual-diff/index.js
@@ -38,7 +38,7 @@ const {
   gitTravisMasterBaseline,
   shortSha,
 } = require('../../common/git');
-const {buildMinifiedRuntime, installPackages} = require('../../common/utils');
+const {buildRuntime, installPackages} = require('../../common/utils');
 const {execScriptAsync} = require('../../common/exec');
 const {isTravisBuild} = require('../../common/travis');
 const {startServer, stopServer} = require('../serve');
@@ -760,7 +760,7 @@ async function ensureOrBuildAmpRuntimeInTestMode_() {
       );
     }
   } else {
-    buildMinifiedRuntime();
+    buildRuntime();
   }
 }
 
diff --git a/build-system/tasks/visual-diff/package.json b/build-system/tasks/visual-diff/package.json
index d8a436d2ade9..4d40f6a5ed69 100644
--- a/build-system/tasks/visual-diff/package.json
+++ b/build-system/tasks/visual-diff/package.json
@@ -6,7 +6,7 @@
   "devDependencies": {
     "@percy/agent": "0.26.2",
     "@percy/puppeteer": "1.1.0",
-    "puppeteer": "3.0.2"
+    "puppeteer": "3.0.4"
   },
   "resolutions": {
     "**/**/minimist": "^1.2.3"
diff --git a/build-system/tasks/visual-diff/yarn.lock b/build-system/tasks/visual-diff/yarn.lock
index cbb479592b84..ddfbba26d527 100644
--- a/build-system/tasks/visual-diff/yarn.lock
+++ b/build-system/tasks/visual-diff/yarn.lock
@@ -194,11 +194,6 @@
     "@types/minimatch" "*"
     "@types/node" "*"
 
-"@types/mime-types@^2.1.0":
-  version "2.1.0"
-  resolved "https://registry.yarnpkg.com/@types/mime-types/-/mime-types-2.1.0.tgz#9ca52cda363f699c69466c2a6ccdaad913ea7a73"
-  integrity sha1-nKUs2jY/aZxpRmwqbM2q2RPqenM=
-
 "@types/minimatch@*":
   version "3.0.3"
   resolved "https://registry.yarnpkg.com/@types/minimatch/-/minimatch-3.0.3.tgz#3dca0e3f33b200fc7d1139c0cd96c1268cadfd9d"
@@ -1452,11 +1447,6 @@ mime-db@1.40.0:
   resolved "https://registry.yarnpkg.com/mime-db/-/mime-db-1.40.0.tgz#a65057e998db090f732a68f6c276d387d4126c32"
   integrity sha512-jYdeOMPy9vnxEqFRRo6ZvTZ8d9oPb+k18PKoYNYUe2stVEBPPwsln/qWzdbmaIvnhZ9v2P+CuecK+fpUfsV2mA==
 
-mime-db@1.43.0:
-  version "1.43.0"
-  resolved "https://registry.yarnpkg.com/mime-db/-/mime-db-1.43.0.tgz#0a12e0502650e473d735535050e7c8f4eb4fae58"
-  integrity sha512-+5dsGEEovYbT8UY9yD7eE4XTc4UwJ1jBYlgaQQF38ENsKR3wj/8q8RFZrF9WIZpB2V1ArTVFUva8sAul1NzRzQ==
-
 mime-db@~1.37.0:
   version "1.37.0"
   resolved "https://registry.yarnpkg.com/mime-db/-/mime-db-1.37.0.tgz#0b6a0ce6fdbe9576e25f1f2d2fde8830dc0ad0d8"
@@ -1469,13 +1459,6 @@ mime-types@^2.1.12, mime-types@~2.1.19:
   dependencies:
     mime-db "~1.37.0"
 
-mime-types@^2.1.25:
-  version "2.1.26"
-  resolved "https://registry.yarnpkg.com/mime-types/-/mime-types-2.1.26.tgz#9c921fc09b7e149a65dfdc0da4d20997200b0a06"
-  integrity sha512-01paPWYgLrkqAyrlDorC1uDwl2p3qZT7yl806vW7DvDoxwXi46jsjFbg+WdwotBIk6/MbEhO/dh5aZ5sNj/dWQ==
-  dependencies:
-    mime-db "1.43.0"
-
 mime-types@~2.1.24:
   version "2.1.24"
   resolved "https://registry.yarnpkg.com/mime-types/-/mime-types-2.1.24.tgz#b6f8d0b3e951efb77dedeca194cff6d16f676f81"
@@ -1700,17 +1683,15 @@ punycode@^2.1.0:
   resolved "https://registry.yarnpkg.com/punycode/-/punycode-2.1.1.tgz#b58b010ac40c22c5657616c8d2c2c02c7bf479ec"
   integrity sha512-XRsRjdf+j5ml+y/6GKHPZbrF/8p2Yga0JPtdqTIY2Xe5ohJPD9saDJJLPvp9+NSBprVvevdXZybnj2cv8OEd0A==
 
-puppeteer@3.0.2:
-  version "3.0.2"
-  resolved "https://registry.yarnpkg.com/puppeteer/-/puppeteer-3.0.2.tgz#1d08cdb7c0c2666f5e743221b1cb1946fea493f0"
-  integrity sha512-5jS/POFVDW9fqb76O8o0IBpXOnq+Na8ocGMggYtnjCRBRqmAFvX0csmwgLOHkYnQ/vCBcBPYlOq0Pp60z1850Q==
+puppeteer@3.0.4:
+  version "3.0.4"
+  resolved "https://registry.yarnpkg.com/puppeteer/-/puppeteer-3.0.4.tgz#f445aae0a6732c65bbb90e963dcd6fd8fde0d780"
+  integrity sha512-1QEb4tJXXbNId7WSHlcDkS3B4GklTIebKn8Y9D6B7tAdUjQncb+8QlTjbQsAgGX5dhRG32Qycuk5XKzJgLs0sg==
   dependencies:
-    "@types/mime-types" "^2.1.0"
     debug "^4.1.0"
     extract-zip "^2.0.0"
     https-proxy-agent "^4.0.0"
     mime "^2.0.3"
-    mime-types "^2.1.25"
     progress "^2.0.1"
     proxy-from-env "^1.0.0"
     rimraf "^3.0.2"
diff --git a/build-system/test-configs/dep-check-config.js b/build-system/test-configs/dep-check-config.js
index 2a486c323235..44ea7e80263a 100644
--- a/build-system/test-configs/dep-check-config.js
+++ b/build-system/test-configs/dep-check-config.js
@@ -251,6 +251,7 @@ exports.rules = [
       // Story education
       'extensions/amp-story-education/0.1/amp-story-education.js->extensions/amp-story/1.0/amp-story-store-service.js',
       'extensions/amp-story-education/0.1/amp-story-education.js->extensions/amp-story/1.0/utils.js',
+      'extensions/amp-story-education/0.1/amp-story-education.js->extensions/amp-story/1.0/amp-story-localization-service.js',
 
       // Subscriptions.
       'extensions/amp-subscriptions/0.1/expr.js->extensions/amp-access/0.1/access-expr.js',
@@ -363,6 +364,10 @@ exports.rules = [
       // For action macros.
       'extensions/amp-link-rewriter/0.1/amp-link-rewriter.js->' +
         'src/service/navigation.js',
+      // For localization.
+      'extensions/amp-story/0.1/amp-story-localization-service.js->src/service/localization.js',
+      'extensions/amp-story/1.0/amp-story-localization-service.js->src/service/localization.js',
+      'extensions/amp-story-auto-ads/0.1/story-ad-localization.js->src/service/localization.js',
       // Accessing calculateScriptBaseUrl() for vendor config URLs
       'extensions/amp-analytics/0.1/config.js->' +
         'src/service/extension-location.js',
diff --git a/examples/amp-consent/cmp-vendors.amp.html b/examples/amp-consent/cmp-vendors.amp.html
index 5d950b4d5d29..e35ff2b2bcd8 100644
--- a/examples/amp-consent/cmp-vendors.amp.html
+++ b/examples/amp-consent/cmp-vendors.amp.html
@@ -101,6 +101,7 @@
           <option>Marfeel</option>
           <option>Ogury</option>
           <option>SourcePoint</option>
+          <option>Usercentrics</option>
         </select>
         <input type="submit" value="Go">
         <button type="button" class="clearLocalStorage" onclick="localStorage.clear(); alert('localStorage Cleared!')">Clear localStorage</button>
@@ -269,6 +270,23 @@ <h3>Image that is NOT blocked by consent</h3>
         </div>
       </amp-consent>
       <!-- End SourcePoint example -->
+
+      <!-- Usercentrics example -->
+      <amp-consent id='consent' layout='nodisplay' type='Usercentrics'>
+        <script type="application/json">
+          {
+            "postPromptUI": "my-consent-prompt-ui",
+            "clientConfig": {
+              "id": "i3_E5TN2b"
+            }
+          }
+        </script>
+        <div id="my-consent-prompt-ui">
+          Post Prompt UI
+          <button on="tap:consent.prompt(consent=Usercentrics)" role="button">Privacy Settings</button>
+        </div>
+      </amp-consent>
+      <!-- End Usercentrics example -->
     </div>
   </body>
 </html>
diff --git a/examples/amp-consent/diy-consent.html b/examples/amp-consent/diy-consent.html
index 57d24d03bada..6dc8139580ad 100644
--- a/examples/amp-consent/diy-consent.html
+++ b/examples/amp-consent/diy-consent.html
@@ -3,7 +3,7 @@
   <head>
     <link rel="stylesheet" type="text/css" href="https://raw.githack.com/ganapativs/bttn.css/master/dist/bttn.min.css">
     <link rel="stylesheet" href="https://unpkg.com/sakura.css/css/sakura.css" type="text/css">
-    <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/animate.css/3.7.2/animate.min.css">
+    <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/animate.css/4.0.0/animate.min.css">
     <style>
 html {
   width: 100%;
diff --git a/examples/amp-story/amp-story-animation.html b/examples/amp-story/amp-story-animation.html
index e7ceef83ead7..f40a4746ec42 100644
--- a/examples/amp-story/amp-story-animation.html
+++ b/examples/amp-story/amp-story-animation.html
@@ -20,6 +20,12 @@
         font-family: sans-serif;
         font-size: 18px;
       }
+      .box {
+        background: blue;
+        width: 80px;
+        height: 100px;
+        margin: 0 0 20px;
+      }
     </style>
   </head>
   <body>
@@ -32,7 +38,7 @@
             fly-in with animate-in, after the previous element
           </div>
         </amp-story-grid-layer>
-        <amp-story-animation layout="nodisplay">
+        <amp-story-animation layout="nodisplay" trigger="visibility">
           <script type="application/json">
             {
               "selector": ".animate",
@@ -53,7 +59,7 @@
             fly-in with animate-in, after the previous element
           </div>
         </amp-story-grid-layer>
-        <amp-story-animation layout="nodisplay">
+        <amp-story-animation layout="nodisplay" trigger="visibility">
           <script type="application/json">
             {
               "selector": ".animate",
@@ -68,6 +74,50 @@
         </amp-story-animation>
       </amp-story-page>
 
+      <amp-story-page id="page2">
+        <amp-story-grid-layer template="vertical">
+          <div class="box animate-bottom-right"></div>
+          <div class="box animate-bottom"></div>
+          <div class="box animate-right"></div>
+        </amp-story-grid-layer>
+        <amp-story-animation layout="nodisplay" trigger="visibility">
+          <script type="application/json">
+            [
+              {
+                "selector": ".animate-bottom",
+                "duration": "2s",
+                "iterations": "infinite",
+                "keyframes": [
+                  {"transform": "none"},
+                  {"transform": "translate(0, calc(100vh - y() - height()))"},
+                  {"transform": "none"}
+                ]
+              },
+              {
+                "selector": ".animate-right",
+                "duration": "2s",
+                "iterations": "infinite",
+                "keyframes": [
+                  {"transform": "none"},
+                  {"transform": "translate(calc(100vw - x() - width()), 0)"},
+                  {"transform": "none"}
+                ]
+              },
+              {
+                "selector": ".animate-bottom-right",
+                "duration": "2s",
+                "iterations": "infinite",
+                "keyframes": [
+                  {"transform": "none"},
+                  {"transform": "translate(calc(100vw - x() - width()), calc(100vh - y() - height()))"},
+                  {"transform": "none"}
+                ]
+              }
+            ]
+          </script>
+        </amp-story-animation>
+      </amp-story-page>
+
       <amp-story-bookend
         src="bookendv1.json"
         layout="nodisplay"
diff --git a/examples/amp-story/reactions.html b/examples/amp-story/reactions.html
index c525640c693d..b134d66cf951 100644
--- a/examples/amp-story/reactions.html
+++ b/examples/amp-story/reactions.html
@@ -1,11 +1,11 @@
 <!doctype html>
-<html ⚡>
+<html ⚡ lang="es">
   <head>
     <meta charset="utf-8">
     <title>Reactions Story</title>
-    <link rel="canonical" href="amp-story-codelab.html">
+    <link rel="canonical" href="reactions.html">
     <meta name="viewport" content="width=device-width,minimum-scale=1,initial-scale=1">
-    <style amp-boilerplate>body{font-family: 'Poppins', sans-serif;-webkit-animation:-amp-start 8s steps(1,end) 0s 1 normal both;-moz-animation:-amp-start 8s steps(1,end) 0s 1 normal both;-ms-animation:-amp-start 8s steps(1,end) 0s 1 normal both;animation:-amp-start 8s steps(1,end) 0s 1 normal both}@-webkit-keyframes -amp-start{from{visibility:hidden}to{visibility:visible}}@-moz-keyframes -amp-start{from{visibility:hidden}to{visibility:visible}}@-ms-keyframes -amp-start{from{visibility:hidden}to{visibility:visible}}@-o-keyframes -amp-start{from{visibility:hidden}to{visibility:visible}}@keyframes -amp-start{from{visibility:hidden}to{visibility:visible}}</style><noscript><style amp-boilerplate>body{-webkit-animation:none;-moz-animation:none;-ms-animation:none;animation:none}</style></noscript>
+    <style amp-boilerplate>body{-webkit-animation:-amp-start 8s steps(1,end) 0s 1 normal both;-moz-animation:-amp-start 8s steps(1,end) 0s 1 normal both;-ms-animation:-amp-start 8s steps(1,end) 0s 1 normal both;animation:-amp-start 8s steps(1,end) 0s 1 normal both}@-webkit-keyframes -amp-start{from{visibility:hidden}to{visibility:visible}}@-moz-keyframes -amp-start{from{visibility:hidden}to{visibility:visible}}@-ms-keyframes -amp-start{from{visibility:hidden}to{visibility:visible}}@-o-keyframes -amp-start{from{visibility:hidden}to{visibility:visible}}@keyframes -amp-start{from{visibility:hidden}to{visibility:visible}}</style><noscript><style amp-boilerplate>body{-webkit-animation:none;-moz-animation:none;-ms-animation:none;animation:none}</style></noscript>
     <script async src="https://cdn.ampproject.org/v0.js"></script>
     <script async custom-element="amp-story" src="https://cdn.ampproject.org/v0/amp-story-1.0.js"></script>
     <script async custom-element="amp-video" src="https://cdn.ampproject.org/v0/amp-video-0.1.js"></script>
@@ -45,16 +45,38 @@ <h2>What is the best story ever?</h2>
           </amp-story-grid-layer>
           <amp-story-grid-layer template="center">
             <amp-story-reaction-quiz
-                animate-in="fly-in-bottom"
+                id="first-cup-dark"
                 endpoint="http://localhost:3000/reactions"
                 theme="dark"
+                chip-corner="sharp">
+              <h1>Who won the first soccer world cup?</h1>
+              <option>France</option>
+              <option>Spain</option>
+              <option correct>Uruguay</option>
+              <option>Brazil</option>
+            </amp-story-reaction-quiz>
+          </amp-story-grid-layer>
+        </amp-story-page>
+        <amp-story-page id="quiz-1b">
+          <amp-story-grid-layer template="fill">
+            <amp-img
+                src="img/roadshow.jpg"
+                layout="responsive"
+                height="1600"
+                width="900">
+            </amp-img>
+          </amp-story-grid-layer>
+          <amp-story-grid-layer template="center">
+            <amp-story-reaction-quiz
+                id="last-cup-dark"
+                theme="dark"
                 style="--reaction-accent-color:#000"
                 chip-corner="sharp">
-              <h1>What is the best city ever?</h1>
-              <option>Tokyo</option>
-              <option>Paris</option>
-              <option correct>Montevideo</option>
-              <option>Mexico City</option>
+              <h1>Who won the last soccer world cup?</h1>
+              <option correct>France</option>
+              <option>Spain</option>
+              <option>Uruguay</option>
+              <option>Brazil</option>
             </amp-story-reaction-quiz>
           </amp-story-grid-layer>
         </amp-story-page>
@@ -69,11 +91,31 @@ <h1>What is the best city ever?</h1>
           </amp-story-grid-layer>
           <amp-story-grid-layer template="center">
             <amp-story-reaction-quiz
+                id="largest-mammal-light"
                 endpoint="http://localhost:3000/reactions"
                 chip-corner="sharp">
-              <h1>What is the best city ever?</h1>
-              <option correct>Montevideo</option>
-              <option>Mexico City</option>
+              <h1>What is the largest mammal?</h1>
+              <option correct>Blue whale</option>
+              <option>Etruscan shrew</option>
+            </amp-story-reaction-quiz>
+          </amp-story-grid-layer>
+        </amp-story-page>
+        <amp-story-page id="quiz-2b">
+          <amp-story-grid-layer template="fill">
+            <amp-img
+                src="img/blue-stuff.jpg"
+                layout="responsive"
+                height="1600"
+                width="900">
+            </amp-img>
+          </amp-story-grid-layer>
+          <amp-story-grid-layer template="center">
+            <amp-story-reaction-quiz
+                id="smallest-mammal-light"
+                chip-corner="sharp">
+              <h1>What is the smallest mammal?</h1>
+              <option>Blue whale</option>
+              <option correct>Etruscan shrew</option>
             </amp-story-reaction-quiz>
           </amp-story-grid-layer>
         </amp-story-page>
diff --git a/examples/amp-subscriptions-iframe.amp.html b/examples/amp-subscriptions-google/amp-subscriptions-iframe.amp.html
similarity index 95%
rename from examples/amp-subscriptions-iframe.amp.html
rename to examples/amp-subscriptions-google/amp-subscriptions-iframe.amp.html
index c075fc329f86..6445a5127c63 100644
--- a/examples/amp-subscriptions-iframe.amp.html
+++ b/examples/amp-subscriptions-google/amp-subscriptions-iframe.amp.html
@@ -28,7 +28,7 @@
       "services": [
         {
           "type": "iframe",
-          "iframeSrc": "//localhost:8000/examples/amp-subscriptions-iframe.provider.html",
+          "iframeSrc": "//localhost:8000/examples/amp-subscriptions-google/amp-subscriptions-iframe.provider.html",
           "iframeVars": [
             "READER_ID",
             "CANONICAL_URL",
@@ -167,6 +167,15 @@
       padding: 16px;
       background: #ffc;
     }
+    
+    amp-subscriptions-dialog {
+      text-align: center;
+      padding: 5px;
+    }
+
+    #subscribebutton {
+      display: inline-block;
+    }
 
   </style>
 </head>
@@ -217,8 +226,8 @@
     <article>
       <figure>
         <amp-img
-            src="img/hero@1x.jpg"
-            srcset="img/hero@1x.jpg 1x, img/hero@2x.jpg 2x"
+            src="../img/hero@1x.jpg"
+            srcset="../img/hero@1x.jpg 1x, ../img/hero@2x.jpg 2x"
             layout="responsive" width="360" placeholder
             alt="Curabitur convallis, urna quis pulvinar feugiat, purus diam posuere turpis, sit amet tincidunt purus justo et mi."
             height="216">
@@ -236,7 +245,7 @@ <h1 itemprop="headline">Lorem Ipsum</h1>
         </header>
 
         <div class="author">
-          <amp-img src="img/sample.jpg" id="author-avatar" placeholder
+          <amp-img src="../img/sample.jpg" id="author-avatar" placeholder
               height="50" width="50">
           </amp-img>
           <div class="byline">
@@ -311,8 +320,8 @@ <h1 itemprop="headline">Lorem Ipsum</h1>
 
           <figure>
             <amp-img class="full-bleed" placeholder
-                src="img/sea@1x.jpg"
-                srcset="img/sea@1x.jpg 1x, img/sea@2x.jpg 2x"
+                src="../img/sea@1x.jpg"
+                srcset="../img/sea@1x.jpg 1x, img/sea@2x.jpg 2x"
                 layout="responsive" width="360"
                 alt="Fusce pretium tempor justo, vitae consequat dolor maximus eget."
                 height="216">
@@ -362,7 +371,7 @@ <h1 itemprop="headline">Lorem Ipsum</h1>
   </template>
   <template type="amp-mustache" subscriptions-dialog subscriptions-display="NOT data.loggedIn">
     <div>Dialog for non logged in users<div>
-    <div subscriptions-display="NOT data.loggedIn"
+    <div id="subscribebutton" subscriptions-display="NOT data.loggedIn"
       subscriptions-action="subscribe"
       subscriptions-service="subscribe.google.com"
       subscriptions-decorate>Login</div>
diff --git a/examples/amp-subscriptions-iframe.provider.html b/examples/amp-subscriptions-google/amp-subscriptions-iframe.provider.html
similarity index 95%
rename from examples/amp-subscriptions-iframe.provider.html
rename to examples/amp-subscriptions-google/amp-subscriptions-iframe.provider.html
index d38687c37703..af82bb9ce982 100644
--- a/examples/amp-subscriptions-iframe.provider.html
+++ b/examples/amp-subscriptions-google/amp-subscriptions-iframe.provider.html
@@ -1,8 +1,8 @@
 <!doctype html>
 <html>
 <head>
-  <script src="../extensions/amp-access/0.1/iframe-api/build/index.js"></script>
-
+  <script src="/extensions/amp-access/0.1/iframe-api/build/index.js"></script>
+  
   <script>
     
     var pageConfig;
diff --git a/examples/amp-subscriptions-smartbox.amp.html b/examples/amp-subscriptions-google/amp-subscriptions-smartbox.amp.html
similarity index 96%
rename from examples/amp-subscriptions-smartbox.amp.html
rename to examples/amp-subscriptions-google/amp-subscriptions-smartbox.amp.html
index 3fadcb4084fd..ecf679b9d9f7 100644
--- a/examples/amp-subscriptions-smartbox.amp.html
+++ b/examples/amp-subscriptions-google/amp-subscriptions-smartbox.amp.html
@@ -215,18 +215,16 @@
     <div class="brand-logo">
       PublisherLogo - Subscriptions Demo
     </div>
+    <p>You need to append "#swg.experiments=smartbox" at the end of the URL and then refresh.</p>
   </header>
 
-
-
-
-
   <h3>"Smart Button (Light)"</h3>
 
     <button id="smartboxButton" subscriptions-display="NOT loggedIn"
       subscriptions-lang="en"
       subscriptions-action="subscribe-smartbutton"
       subscriptions-service="subscribe.google.com"
+      subscriptions-message-number="1"
       subscriptions-decorate>Yes I will Contribute</button>
 
   <h3>"Smart Button (Dark)"</h3>
@@ -235,6 +233,7 @@ <h3>"Smart Button (Dark)"</h3>
       subscriptions-lang="en"
       subscriptions-action="subscribe-smartbutton-dark"
       subscriptions-service="subscribe.google.com"
+      subscriptions-message-number="1"
       subscriptions-decorate>Yes I will Contribute</button>
 
   <h3>"Smart Button (Dark w/ custom message text color)"</h3>
@@ -244,8 +243,8 @@ <h3>"Smart Button (Dark w/ custom message text color)"</h3>
       subscriptions-action="subscribe-smartbutton-dark"
       subscriptions-service="subscribe.google.com"
       subscriptions-message-text-color="rgba(0, 120, 255, 0.95)"
+      subscriptions-message-number="1"
       subscriptions-decorate>Yes I will Contribute</button>
     
-
 </body>
 </html>
diff --git a/examples/analytics-vendors.amp.html b/examples/analytics-vendors.amp.html
index 2fe9c6596180..04d138201fe3 100644
--- a/examples/analytics-vendors.amp.html
+++ b/examples/analytics-vendors.amp.html
@@ -53,6 +53,7 @@
       <option>atinternet</option>
       <option>afsanalytics</option>
       <option>baiduanalytics</option>
+      <option>blueconic</option>
       <option>browsi</option>
       <option>burt</option>
       <option>byside</option>
@@ -337,18 +338,40 @@
 </amp-analytics>
 <!-- Baidu stats example -->
 
-  <!-- Browsi prediction tracking example -->
-  <amp-analytics type="browsi" id="browsi">
-    <script type="application/json">
-      {
-        "vars": {
-          "pubKey": "demo-pub",
-          "siteKey": "demo-site"
+<!-- BlueConic analytics tracking -->
+<amp-analytics type="blueconic" id="blueconic">
+  <script type="application/json">
+    {
+      "triggers": {
+        "pageView": {
+          "on": "visible",
+          "request": "event",
+          "vars": {
+            "pixelId": "your-pixel-id"
+          }
         }
+      },
+      "vars": {
+        "tenantId": "your-tenant-url",
+        "property": "your-property"
       }
-    </script>
-  </amp-analytics>
-  <!-- End Browsi prediction tracking example -->
+    }
+  </script>
+</amp-analytics>
+<!-- End BlueConic analytics example -->
+
+<!-- Browsi prediction tracking example -->
+<amp-analytics type="browsi" id="browsi">
+  <script type="application/json">
+    {
+      "vars": {
+        "pubKey": "demo-pub",
+        "siteKey": "demo-site"
+      }
+    }
+  </script>
+</amp-analytics>
+<!-- End Browsi prediction tracking example -->
 
 <!-- Burt tracking -->
 <amp-analytics type="burt" id="burt">
diff --git a/extensions/amp-3d-gltf/amp-3d-gltf.md b/extensions/amp-3d-gltf/amp-3d-gltf.md
index c97fd927193e..4658f75f1748 100644
--- a/extensions/amp-3d-gltf/amp-3d-gltf.md
+++ b/extensions/amp-3d-gltf/amp-3d-gltf.md
@@ -28,7 +28,9 @@ limitations under the License.
 
 The `amp-3d-gltf` component displays 3D models that are in gITF format.
 
-**Note**: A WebGL capable browser is required to display these models.
+[tip type="note"]
+You must use a [WebGL](https://developer.mozilla.org/en-US/docs/Web/API/WebGL_API)-capable browser to display 3D models.
+[/tip]
 
 ### Example
 
@@ -43,67 +45,90 @@ The `amp-3d-gltf` component displays 3D models that are in gITF format.
 ></amp-3d-gltf>
 ```
 
-### Limitations
+### Compatibility
 
-Currently, only works with glTF 2.0.
+The component supports [glTF 2.0](https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#cameras),
+with the following exceptions:
 
-Unsupported features:
+- Embedded cameras
+- Animation
 
-- embeded cameras
-- animation
+### Set CORS headers
 
-### CORS
-
-`amp-3d-gltf` makes a `fetch` request from the origin `https://<random>.ampproject.net` so `access-control-allow-origin: *.ampproject.net` must be set on the response header of the endpoint specified as `src`. Wildcard is needed since the origin has a random sub-domain component to it.
+The `amp-3d-gltf` component makes a fetch request to the origin from
+`https://<random>.ampproject.net` when it requests the gltf file. Set
+`access-control-allow-origin:*.ampproject.net` on the response header of the
+`src` endpoint to avoid
+[CORS issues when served from an AMP cache](https://amp.dev/documentation/guides-and-tutorials/learn/amp-caches-and-cors/amp-cors-requests/?format=websites).
+Use a wildcard character to address the `<random>` subdomain component.
 
 ## Attributes
 
-<table>
-  <tr>
-    <td width="40%"><strong>src [required]</strong></td>
-    <td>A required attribute that specifies the URL to the gltf file.</td>
-  </tr>
-  <tr>
-    <td width="40%"><strong>alpha [optional]</strong></td>
-    <td>A Boolean attribute that specifies whether free space on canvas is transparent. By default, free space is filled with black.
-Default value is <code>false</code>.</td>
-  </tr>
-  <tr>
-    <td width="40%"><strong>antialiasing [optional]</strong></td>
-    <td>A Boolean attribute that specifies whether to turn on antialiasing. Default value is <code>false</code>.</td>
-  </tr>
-  <tr>
-    <td width="40%"><strong>clearColor [optional]</strong></td>
-    <td>A string that must contain valid CSS color, that will be used to fill free space on canvas.</td>
-  </tr>
-  <tr>
-    <td width="40%"><strong>maxPixelRatio [optional]</strong></td>
-    <td>A numeric value that specifies the upper limit for the pixelRatio render option. The default is <code>window.devicePixelRatio</code>.</td>
-  </tr>
-  <tr>
-    <td width="40%"><strong>autoRotate [optional]</strong></td>
-    <td>A Boolean attribute that specifies whether to automatically rotate the camera around the model's center. Default value is <code>false</code>.</td>
-  </tr>
-  <tr>
-    <td width="40%"><strong>enableZoom [optional]</strong></td>
-    <td>A Boolean attribute that specifies whether to turn on zoom. Default value is <code>true</code>.</td>
-  </tr>
-</table>
+### src
+
+The `src` attribute specifies the gltf file location.
+
+### alpha (optional)
+
+Use the `alpha` attribute to specify the behavior of the canvas background.
+This attribute takes a boolean value. To enable transparency instead of the
+default white, set the value to `true`.
+
+### antialiasing (optional)
+
+Use the `antialiasing` attribute to specify whether to enable antialiasing. To
+enable antialiasing, set the value to true.
+
+### clearColor (optional)
+
+The `clearColor` attribute specifies a CSS color, such as #FF8C00. This color
+fills free space on the canvas.
+
+### maxPixelRatio (optional)
+
+The `maxPixelRatio` attribute specifies an upper limit for the `pixelRatio`
+render option. It defaults to `window.devicePixelRatio`.
+
+### autoRotate (optional)
+
+Use the `autoRotate` attribute to enable automatic rotation around the model's
+center. To enable rotation, set the value to `true`. `autorotate` defaults to
+`false`.
+
+### enableZoom (optional)
+
+Use the `enableZoom` attribute to disable zooming in and out of the model. To
+disable zoom, set the value to `false`. `autororate` defaults to `true`.
 
 ## Actions
 
-<table>
-  <tr>
-    <td width="40%"><strong>setModelRotation(x, y, z, xMin, xMax, yMin, yMax, zMin, zMax)</strong></td>
-    <td>sets model rotation. rotation order is ZYX
-    <ul>
-      <li>x/y/z - number 0..1, defaults to previous value of model rotation.</li>
-      <li>min/max - angle in radians, defaults to 0 / pi * 2, defines target range</li>
-      </ul>
-    for example `setModelRotation(x=0.5, xMin=0, xMax=3.14)` will change `x` component of rotation to `1.57`.</td>
-  </tr>
-</table>
+### setModelRotation
+
+The `setModelRotation` action specifies the model's rotation. The rotation order
+is ZYX.
+
+- Specify the rotation value of the x, y, and/or z axis with `x`, `y`, and/or
+  `z` arguments. This action accepts a number between 0 and 1. It defaults to the
+  previous value.
+- Specify the angle of rotation in radians with `xMin`, `xMax`, `yMin`, `yMax`,
+  and/or `zMin`, `zMax` arguments. Use a min and a max to define the target range.
+  The angle range defaults to `0 / pi * 2`.
+
+The following action changes the x axis of the component’s rotation to 1.57 when fired.
+
+```json
+setModelRotation((x = 0.5), (xMin = 0), (xMax = 3.14))
+```
+
+## Styling
+
+Here are a few things to keep in mind for style:
+
+- The `alpha` attribute specifies transparency.
+- The `clearColor` attribute specifies the color of the background if it isn't transparent.
+- `amp-3d-gltf` defaults to a white background if you don't specify a background color.
 
 ## Validation
 
-See [amp-3d-gltf rules](https://github.com/ampproject/amphtml/blob/master/extensions/amp-3d-gltf/validator-amp-3d-gltf.protoascii) in the AMP validator specification.
+See [amp-3d-gltf rules](https://github.com/ampproject/amphtml/blob/master/extensions/amp-3d-gltf/validator-amp-3d-gltf.protoascii)
+in the AMP validator specification.
diff --git a/extensions/amp-a4a/0.1/callout-vendors.js b/extensions/amp-a4a/0.1/callout-vendors.js
index a9ae2d673d82..989acfd1ef93 100644
--- a/extensions/amp-a4a/0.1/callout-vendors.js
+++ b/extensions/amp-a4a/0.1/callout-vendors.js
@@ -114,6 +114,12 @@ const RTC_VENDORS = jsonConfiguration({
     macros: ['PLACEMENT_ID', 'DIV_ID'],
     disableKeyAppend: true,
   },
+  glxm: {
+    url:
+      'https://pbserver.galaxiemedia.fr/openrtb2/amp?tag_id=REQUEST_ID&w=ATTR(width)&h=ATTR(height)&ow=ATTR(data-override-width)&oh=ATTR(data-override-height)&ms=ATTR(data-multi-size)&slot=ATTR(data-slot)&targeting=TGT&curl=CANONICAL_URL&timeout=TIMEOUT&adc=ADCID&purl=HREF&gdpr_consent=CONSENT_STRING&account=ACCOUNT_ID',
+    macros: ['REQUEST_ID', 'CONSENT_STRING', 'ACCOUNT_ID'],
+    disableKeyAppend: true,
+  },
   aps: {
     url:
       'https://aax.amazon-adsystem.com/e/dtb/bid?src=PUB_ID&pubid=PUB_UUID&amp=1&u=CANONICAL_URL&slots=%5B%7B%22sd%22%3A%22ATTR(data-slot)%22%2C%22s%22%3A%5B%22ATTR(width)xATTR(height)%22%5D%2C%22ms%22%3A%22ATTR(data-multi-size)%22%7D%5D&pj=PARAMS&gdprc=CONSENT_STRING',
diff --git a/extensions/amp-a4a/rtc-documentation.md b/extensions/amp-a4a/rtc-documentation.md
index e668d5e9b6ed..e82536ad4ef7 100644
--- a/extensions/amp-a4a/rtc-documentation.md
+++ b/extensions/amp-a4a/rtc-documentation.md
@@ -135,6 +135,7 @@ The `errorReportingUrl` property is optional. The only available macros are ERRO
 - The Ozone Project
 - PubMatic OpenWrap
 - Purch
+- Galaxie Media
 - Rubicon
 - Salesforce
 - Yieldbot
diff --git a/extensions/amp-access/0.1/iframe-api/package.json b/extensions/amp-access/0.1/iframe-api/package.json
index f5777e84e904..04df0527d93d 100644
--- a/extensions/amp-access/0.1/iframe-api/package.json
+++ b/extensions/amp-access/0.1/iframe-api/package.json
@@ -16,7 +16,7 @@
   "devDependencies": {
     "babel-plugin-external-helpers": "6.22.0",
     "babel-preset-env": "1.7.0",
-    "rollup": "2.7.5",
+    "rollup": "2.9.1",
     "rollup-plugin-babel": "4.4.0",
     "rollup-plugin-cleanup": "3.1.1"
   }
diff --git a/extensions/amp-access/amp-access.md b/extensions/amp-access/amp-access.md
index 2322bcf2cf80..25665d18372d 100644
--- a/extensions/amp-access/amp-access.md
+++ b/extensions/amp-access/amp-access.md
@@ -200,7 +200,7 @@ It is possible to specify multiple access providers using an array instead of a
       "namespace": value
     },
     ...
-  [
+  ]
 </script>
 ```
 
diff --git a/extensions/amp-accordion/0.1/amp-accordion.js b/extensions/amp-accordion/0.1/amp-accordion.js
index f79e764ca7b7..e647d43c2ada 100644
--- a/extensions/amp-accordion/0.1/amp-accordion.js
+++ b/extensions/amp-accordion/0.1/amp-accordion.js
@@ -82,6 +82,11 @@ class AmpAccordion extends AMP.BaseElement {
     return layout == Layout.CONTAINER;
   }
 
+  /** @override */
+  prerenderAllowed() {
+    return true;
+  }
+
   /** @override */
   buildCallback() {
     this.action_ = Services.actionServiceForDoc(this.element);
diff --git a/extensions/amp-action-macro/amp-action-macro.md b/extensions/amp-action-macro/amp-action-macro.md
index 7b69c2e18204..e672b3e5d020 100644
--- a/extensions/amp-action-macro/amp-action-macro.md
+++ b/extensions/amp-action-macro/amp-action-macro.md
@@ -4,6 +4,7 @@ formats:
   - websites
 teaser:
   text: Creates reusable actions.
+experimental: true
 ---
 
 <!---
@@ -21,25 +22,23 @@ limitations under the License.
 
 # amp-action-macro
 
-## Overview
-
 The `amp-action-macro` component allows for the creation of reusable actions.
 
-## Example
+## Usage
+
+`amp-action-macro` creates AMP action macros that you can reuse as needed. Each
+action macro needs an `id` and an action to `execute`. You can call the action
+macro by its `id` and pass it arguments that alter its behavior.
+
+### Example
 
 ```html
 <amp-action-macro
   id="closeNavigations"
   execute="AMP.setState({nav1: 'close', nav2: 'close})"
 ></amp-action-macro>
-```
-
-```html
 <button on="tap:closeNavigations.execute()">Close all</button>
 <div on="tap:closeNavigations.execute()">Close all</div>
-```
-
-```html
 <!--
   You can provide arguments in the macro.
 -->
@@ -50,9 +49,6 @@ The `amp-action-macro` component allows for the creation of reusable actions.
   execute="carousel.goToSlide(index=foo), carousel.goToSlide(index=bar)"
   arguments="foo, bar"
 ></amp-action-macro>
-```
-
-```html
 <button on="tap:carousel-macro.execute(foo=1, bar=2)">
   Go to slide 1 then 2
 </button>
@@ -60,20 +56,19 @@ The `amp-action-macro` component allows for the creation of reusable actions.
 
 ## Attributes
 
-##### id
-
-Used to uniquely identify the action. This is referenced in an action invocation.
+### id
 
-##### execute
+Used to uniquely identify the action. This `id` is referenced in an action invocation.
 
-The action to invoke. Any valid amp action is allowed here. See [actions and events in AMP](https://amp.dev/documentation/guides-and-tutorials/learn/amp-actions-and-events).
+### execute
 
-e.g.
+The action to invoke. Any [valid amp action](https://amp.dev/documentation/guides-and-tutorials/learn/amp-actions-and-events)
+is allowed here.
 
 ```html
 <amp-action-macro
   id="navigate-action"
-  action="AMP.navigateTo('http://www.ampproject.org')"
+  execute="AMP.navigateTo('http://www.ampproject.org')"
 ></amp-action-macro>
 
 <amp-action-macro
@@ -87,7 +82,7 @@ e.g.
 <button on="tap:refresh-amp-list"></button>
 ```
 
-##### arguments
+### arguments
 
-Used to define arguments that can be used in the called invocation and substituted
-in the amp action macro call.
+Used to define arguments that can be used in the called invocation and
+substituted in the amp action macro call.
diff --git a/extensions/amp-ad-exit/0.1/amp-ad-exit.js b/extensions/amp-ad-exit/0.1/amp-ad-exit.js
index 22685fe216c2..ac08d1d7087e 100644
--- a/extensions/amp-ad-exit/0.1/amp-ad-exit.js
+++ b/extensions/amp-ad-exit/0.1/amp-ad-exit.js
@@ -440,7 +440,7 @@ export class AmpAdExit extends AMP.BaseElement {
 
   /**
    * amp-analytics will create an iframe for vendors in
-   * extensions/amp-analytics/0.1/vendors.js who have transport/iframe defined.
+   * extensions/amp-analytics/0.1/vendors/* who have transport/iframe defined.
    * This is limited to MRC-accreddited vendors. The frame is removed in
    * amp-analytics, and the listener is destroyed here, if the user
    * navigates/swipes away from the page. Both are recreated if the user
diff --git a/extensions/amp-ad-network-doubleclick-impl/0.1/amp-ad-network-doubleclick-impl.js b/extensions/amp-ad-network-doubleclick-impl/0.1/amp-ad-network-doubleclick-impl.js
index 26a18aeaf90a..cd5fa6be9fe6 100644
--- a/extensions/amp-ad-network-doubleclick-impl/0.1/amp-ad-network-doubleclick-impl.js
+++ b/extensions/amp-ad-network-doubleclick-impl/0.1/amp-ad-network-doubleclick-impl.js
@@ -334,6 +334,51 @@ export class AmpAdNetworkDoubleclickImpl extends AmpA4A {
     this.inZIndexHoldBack_ = false;
   }
 
+  /**
+   * @return {number|boolean} render on idle configuration with false
+   *    indicating disabled.
+   * @private
+   */
+  getIdleRenderEnabled_() {
+    if (this.isIdleRender_) {
+      return this.isIdleRender_;
+    }
+    // Disable if publisher has indicated a non-default loading strategy.
+    if (this.element.getAttribute('data-loading-strategy')) {
+      return false;
+    }
+    const expVal = this.postAdResponseExperimentFeatures['render-idle-vp'];
+    const vpRange = parseInt(expVal, 10);
+    if (expVal && isNaN(vpRange)) {
+      // holdback branch sends non-numeric value.
+      return false;
+    }
+    return vpRange || 12;
+  }
+
+  /** @override */
+  idleRenderOutsideViewport() {
+    const vpRange = this.getIdleRenderEnabled_();
+    if (vpRange === false) {
+      return vpRange;
+    }
+    const renderOutsideViewport = this.renderOutsideViewport();
+    // False will occur when throttle in effect.
+    if (typeof renderOutsideViewport === 'boolean') {
+      return renderOutsideViewport;
+    }
+    this.isIdleRender_ = true;
+    // NOTE(keithwrightbos): handle race condition where previous
+    // idleRenderOutsideViewport marked slot as idle render despite never
+    // being schedule due to being beyond viewport max offset.  If slot
+    // comes within standard outside viewport range, then ensure throttling
+    // will not be applied.
+    this.getResource()
+      .whenWithinViewport(renderOutsideViewport)
+      .then(() => (this.isIdleRender_ = false));
+    return vpRange;
+  }
+
   /** @override */
   isLayoutSupported(layout) {
     this.isFluidPrimaryRequest_ = layout == Layout.FLUID;
@@ -383,7 +428,7 @@ export class AmpAdNetworkDoubleclickImpl extends AmpA4A {
         branches: Object.values(ZINDEX_EXP_BRANCHES),
       },
       [RANDOM_SUBDOMAIN_SAFEFRAME_EXP]: {
-        ifTrafficEligible: () => true,
+        isTrafficEligible: () => true,
         branches: [
           RANDOM_SUBDOMAIN_SAFEFRAME_BRANCHES.CONTROL,
           RANDOM_SUBDOMAIN_SAFEFRAME_BRANCHES.EXPERIMENT,
diff --git a/extensions/amp-ad-network-doubleclick-impl/0.1/test/test-amp-ad-network-doubleclick-impl.js b/extensions/amp-ad-network-doubleclick-impl/0.1/test/test-amp-ad-network-doubleclick-impl.js
index 412201372ed1..cad58b3f61e3 100644
--- a/extensions/amp-ad-network-doubleclick-impl/0.1/test/test-amp-ad-network-doubleclick-impl.js
+++ b/extensions/amp-ad-network-doubleclick-impl/0.1/test/test-amp-ad-network-doubleclick-impl.js
@@ -1725,6 +1725,100 @@ describes.realWin(
       });
     });
 
+    describe('#idleRenderOutsideViewport', () => {
+      beforeEach(() => {
+        element = createElementWithAttributes(doc, 'amp-ad', {
+          'width': '200',
+          'height': '50',
+          'type': 'doubleclick',
+        });
+        impl = new AmpAdNetworkDoubleclickImpl(element);
+        env.sandbox
+          .stub(impl, 'getResource')
+          .returns({whenWithinViewport: () => Promise.resolve()});
+      });
+
+      it('should use experiment value', () => {
+        impl.postAdResponseExperimentFeatures['render-idle-vp'] = '4';
+        expect(impl.idleRenderOutsideViewport()).to.equal(4);
+        expect(impl.isIdleRender_).to.be.true;
+      });
+
+      it('should return false if using loading strategy', () => {
+        impl.postAdResponseExperimentFeatures['render-idle-vp'] = '4';
+        impl.element.setAttribute(
+          'data-loading-strategy',
+          'prefer-viewability-over-views'
+        );
+        expect(impl.idleRenderOutsideViewport()).to.be.false;
+        expect(impl.isIdleRender_).to.be.false;
+      });
+
+      it('should return false if invalid experiment value', () => {
+        impl.postAdResponseExperimentFeatures['render-idle-vp'] = 'abc';
+        expect(impl.idleRenderOutsideViewport()).to.be.false;
+      });
+
+      it('should return 12 if no experiment header', () => {
+        expect(impl.idleRenderOutsideViewport()).to.equal(12);
+      });
+
+      it('should return renderOutsideViewport boolean', () => {
+        env.sandbox.stub(impl, 'renderOutsideViewport').returns(false);
+        expect(impl.idleRenderOutsideViewport()).to.be.false;
+      });
+    });
+
+    describe('idle renderNonAmpCreative', () => {
+      beforeEach(() => {
+        element = createElementWithAttributes(doc, 'amp-ad', {
+          'width': '200',
+          'height': '50',
+          'type': 'doubleclick',
+        });
+        impl = new AmpAdNetworkDoubleclickImpl(element);
+        impl.postAdResponseExperimentFeatures['render-idle-vp'] = '4';
+        impl.postAdResponseExperimentFeatures['render-idle-throttle'] = 'true';
+        env.sandbox
+          .stub(AmpA4A.prototype, 'renderNonAmpCreative')
+          .returns(Promise.resolve());
+      });
+
+      // TODO(jeffkaufman, #13422): this test was silently failing
+      it.skip('should throttle if idle render and non-AMP creative', () => {
+        impl.win['3pla'] = 1;
+        const startTime = Date.now();
+        return impl.renderNonAmpCreative().then(() => {
+          expect(Date.now() - startTime).to.be.at.least(1000);
+        });
+      });
+
+      it('should NOT throttle if idle experiment not enabled', () => {
+        impl.win['3pla'] = 1;
+        delete impl.postAdResponseExperimentFeatures['render-idle-vp'];
+        const startTime = Date.now();
+        return impl.renderNonAmpCreative().then(() => {
+          expect(Date.now() - startTime).to.be.at.most(50);
+        });
+      });
+
+      it('should NOT throttle if experiment throttle not enabled', () => {
+        impl.win['3pla'] = 1;
+        const startTime = Date.now();
+        return impl.renderNonAmpCreative().then(() => {
+          expect(Date.now() - startTime).to.be.at.most(50);
+        });
+      });
+
+      it('should NOT throttle if idle render and no previous', () => {
+        impl.win['3pla'] = 0;
+        const startTime = Date.now();
+        return impl.renderNonAmpCreative().then(() => {
+          expect(Date.now() - startTime).to.be.at.most(50);
+        });
+      });
+    });
+
     describe('#preconnect', () => {
       beforeEach(() => {
         element = createElementWithAttributes(doc, 'amp-ad', {
diff --git a/extensions/amp-analytics/0.1/config.js b/extensions/amp-analytics/0.1/config.js
index d745f7eff9a7..c5093ea459f0 100644
--- a/extensions/amp-analytics/0.1/config.js
+++ b/extensions/amp-analytics/0.1/config.js
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-import {ANALYTICS_CONFIG} from './vendors';
+import {DEFAULT_CONFIG} from './default-config';
 import {Services} from '../../../src/services';
 import {assertHttpsUrl} from '../../../src/url';
 import {calculateScriptBaseUrl} from '../../../src/service/extension-location';
@@ -40,10 +40,13 @@ export class AnalyticsConfig {
     this.win_ = null;
 
     /**
-     * @const {!JsonObject} Copied here for tests.
+     * @const {!JsonObject}
      * @private
      */
-    this.predefinedConfig_ = ANALYTICS_CONFIG;
+    this.defaultConfig_ = DEFAULT_CONFIG || dict();
+
+    /** @private {!JsonObject} */
+    this.vendorConfig_ = dict();
 
     /**
      * @private {JsonObject}
@@ -115,7 +118,7 @@ export class AnalyticsConfig {
       .then((res) => res.json())
       .then(
         (jsonValue) => {
-          this.predefinedConfig_[type] = jsonValue;
+          this.vendorConfig_ = jsonValue || dict();
           dev().fine(TAG, 'Vendor config loaded for ' + type, jsonValue);
         },
         (err) => {
@@ -336,7 +339,7 @@ export class AnalyticsConfig {
    * Order of precedence for configs from highest to lowest:
    * - Remote config: specified through an attribute of the tag.
    * - Inline config: specified insize the tag.
-   * - Predefined config: Defined as part of the platform.
+   * - Predefined Vendor config: Defined as part of the platform.
    * - Default config: Built-in config shared by all amp-analytics tags.
    *
    * @private
@@ -350,17 +353,16 @@ export class AnalyticsConfig {
         'requestCount': 0,
       },
     });
-    const defaultConfig = this.predefinedConfig_['default'] || {};
-    mergeObjects(expandConfigRequest(defaultConfig), config);
+    mergeObjects(expandConfigRequest(this.defaultConfig_), config);
     mergeObjects(
-      expandConfigRequest(this.getTypeConfig_()),
+      expandConfigRequest(this.vendorConfig_),
       config,
-      /* predefined */ true
+      /* predefined-vendor */ true
     );
     mergeObjects(
       expandConfigRequest(rewrittenConfig),
       config,
-      /* predefined */ true
+      /* predefined-vendor */ true
     );
     return config;
   }
@@ -370,16 +372,7 @@ export class AnalyticsConfig {
    * @return {!JsonObject}
    */
   getConfigRewriter_() {
-    return this.getTypeConfig_()['configRewriter'] || {};
-  }
-
-  /**
-   * Reads a vendor configuration.
-   * @return {!JsonObject}
-   */
-  getTypeConfig_() {
-    const type = this.element_.getAttribute('type');
-    return this.predefinedConfig_[type] || {};
+    return this.vendorConfig_['configRewriter'] || {};
   }
 
   /**
@@ -412,8 +405,7 @@ export class AnalyticsConfig {
    * @param {!JsonObject} inlineConfig
    */
   validateTransport_(inlineConfig) {
-    const type = this.element_.getAttribute('type');
-    if (this.predefinedConfig_[type]) {
+    if (this.vendorConfig_) {
       // TODO(zhouyx, #7096) Track overwrite percentage. Prevent transport
       // overwriting
       if (inlineConfig['transport'] || this.remoteConfig_['transport']) {
@@ -494,19 +486,19 @@ export class AnalyticsConfig {
  *
  * @param {Object|Array} from Object or array to merge from
  * @param {Object|Array} to Object or Array to merge into
- * @param {boolean=} opt_predefinedConfig
+ * @param {boolean=} opt_predefinedVendorConfig
  * @return {*} TODO(#23582): Specify return type
  */
-export function mergeObjects(from, to, opt_predefinedConfig) {
+export function mergeObjects(from, to, opt_predefinedVendorConfig) {
   if (to === null || to === undefined) {
     to = {};
   }
 
-  // Assert that optouts are allowed only in predefined configs.
+  // Assert that optouts are allowed only in predefined vendor configs.
   // The last expression adds an exception of known, safe optout function
   // that is already being used in the wild.
   userAssert(
-    opt_predefinedConfig ||
+    opt_predefinedVendorConfig ||
       !from ||
       !from['optout'] ||
       from['optout'] == '_gaUserPrefs.ioo' ||
@@ -516,7 +508,7 @@ export function mergeObjects(from, to, opt_predefinedConfig) {
 
   for (const property in from) {
     userAssert(
-      opt_predefinedConfig || property != 'iframePing',
+      opt_predefinedVendorConfig || property != 'iframePing',
       'iframePing config is only available to vendor config.'
     );
     // Only deal with own properties.
@@ -528,7 +520,7 @@ export function mergeObjects(from, to, opt_predefinedConfig) {
         to[property] = mergeObjects(
           from[property],
           to[property],
-          opt_predefinedConfig
+          opt_predefinedVendorConfig
         );
       } else if (isObject(from[property])) {
         if (!isObject(to[property])) {
@@ -537,7 +529,7 @@ export function mergeObjects(from, to, opt_predefinedConfig) {
         to[property] = mergeObjects(
           from[property],
           to[property],
-          opt_predefinedConfig
+          opt_predefinedVendorConfig
         );
       } else {
         to[property] = from[property];
diff --git a/extensions/amp-analytics/0.1/vendors.js b/extensions/amp-analytics/0.1/default-config.js
similarity index 92%
rename from extensions/amp-analytics/0.1/vendors.js
rename to extensions/amp-analytics/0.1/default-config.js
index 9ac3b0917059..d490ddf80433 100644
--- a/extensions/amp-analytics/0.1/vendors.js
+++ b/extensions/amp-analytics/0.1/default-config.js
@@ -14,14 +14,10 @@
  * limitations under the License.
  */
 
-import {
-  includeJsonLiteral,
-  jsonConfiguration,
-  jsonLiteral,
-} from '../../../src/json';
+import {jsonConfiguration} from '../../../src/json';
 
 // TODO(zhouyx@: Rename file and object name)
-const DEFAULT_CONFIG = jsonLiteral({
+const defaultConfig = jsonConfiguration({
   'transport': {'beacon': true, 'xhrpost': true, 'image': true},
   'vars': {
     'accessReaderId': 'ACCESS_READER_ID',
@@ -91,11 +87,7 @@ const DEFAULT_CONFIG = jsonLiteral({
   },
 });
 
-const analyticsConfig = jsonConfiguration({
-  'default': includeJsonLiteral(DEFAULT_CONFIG),
-});
-
 /**
  * @const {!JsonObject}
  */
-export const ANALYTICS_CONFIG = analyticsConfig;
+export const DEFAULT_CONFIG = defaultConfig;
diff --git a/extensions/amp-analytics/0.1/linker-manager.js b/extensions/amp-analytics/0.1/linker-manager.js
index 8224877fcd0f..e7f6579181ee 100644
--- a/extensions/amp-analytics/0.1/linker-manager.js
+++ b/extensions/amp-analytics/0.1/linker-manager.js
@@ -14,6 +14,7 @@
  * limitations under the License.
  */
 
+import {AMPDOC_SINGLETON_NAME} from '../../../src/enums';
 import {ExpansionOptions, variableServiceForDoc} from './variables';
 import {Priority} from '../../../src/service/navigation';
 import {Services} from '../../../src/services';
@@ -29,9 +30,6 @@ import {user} from '../../../src/log';
 /** @const {string} */
 const TAG = 'amp-analytics/linker-manager';
 
-/** @const {string} */
-const LINKER_CREATED = 'i-amphtml-linker-created';
-
 export class LinkerManager {
   /**
    * @param {!../../../src/service/ampdoc-impl.AmpDoc} ampdoc
@@ -232,20 +230,7 @@ export class LinkerManager {
       return false;
     }
 
-    const headNode = this.ampdoc_.getHeadNode();
-    const linkerCreatedEl =
-      headNode instanceof ShadowRoot
-        ? this.ampdoc_.getBody()
-        : headNode.querySelector(
-            'meta[name="amp-google-client-id-api"][content="googleanalytics"]'
-          );
-
-    if (linkerCreatedEl.hasAttribute(LINKER_CREATED)) {
-      return false;
-    }
-
-    linkerCreatedEl.setAttribute(LINKER_CREATED, '');
-    return true;
+    return this.ampdoc_.registerSingleton(AMPDOC_SINGLETON_NAME.LINKER);
   }
 
   /**
diff --git a/extensions/amp-analytics/0.1/test/test-config-new.js b/extensions/amp-analytics/0.1/test/test-config.js
similarity index 100%
rename from extensions/amp-analytics/0.1/test/test-config-new.js
rename to extensions/amp-analytics/0.1/test/test-config.js
diff --git a/extensions/amp-analytics/0.1/test/test-vendors-new.js b/extensions/amp-analytics/0.1/test/test-vendors-new.js
deleted file mode 100644
index 0b3190e672c3..000000000000
--- a/extensions/amp-analytics/0.1/test/test-vendors-new.js
+++ /dev/null
@@ -1,254 +0,0 @@
-/**
- * Copyright 2019 The AMP HTML Authors. All Rights Reserved.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS-IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-import {AmpAnalytics} from '../amp-analytics';
-import {AnalyticsConfig} from '../config';
-import {ExpansionOptions, variableServiceForDoc} from '../variables';
-import {IFRAME_TRANSPORTS} from '../iframe-transport-vendors';
-import {
-  ImagePixelVerifier,
-  mockWindowInterface,
-} from '../../../../testing/test-helper';
-import {Services} from '../../../../src/services';
-import {hasOwn} from '../../../../src/utils/object';
-import {macroTask} from '../../../../testing/yield';
-
-/* global require: false */
-const VENDOR_REQUESTS = require('./vendor-requests.json');
-
-describes.realWin(
-  'amp-analytics',
-  {
-    amp: {
-      extensions: ['amp-analytics'],
-    },
-    mockFetch: false,
-  },
-  function (env) {
-    let win, doc;
-    let requestVerifier;
-    let elementMacros;
-
-    beforeEach(() => {
-      win = env.win;
-      doc = win.document;
-      const wi = mockWindowInterface(env.sandbox);
-      wi.getLocation.returns(win.location);
-      requestVerifier = new ImagePixelVerifier(wi);
-      elementMacros = {
-        'COOKIE': null,
-        'CONSENT_STATE': null,
-      };
-    });
-
-    describe('Should not contain iframe transport if not whitelisted', () => {
-      for (const vendor in VENDOR_REQUESTS) {
-        it('test vendor: ' + vendor, () => {
-          const el = doc.createElement('amp-analytics');
-          el.setAttribute('type', vendor);
-          doc.body.appendChild(el);
-          const analyticsConfig = new AnalyticsConfig(el);
-          return analyticsConfig.loadConfig().then((config) => {
-            if (
-              hasOwn(config, 'transport') &&
-              hasOwn(config.transport, 'iframe')
-            ) {
-              expect(config['transport']['iframe']).to.equal(
-                IFRAME_TRANSPORTS[vendor]
-              );
-            }
-          });
-        });
-      }
-    });
-
-    describe('vendor request tests', () => {
-      for (const vendor in VENDOR_REQUESTS) {
-        describe('analytics vendor: ' + vendor, function () {
-          let config;
-          let analytics;
-          beforeEach((done) => {
-            const urlReplacements = Services.urlReplacementsForDoc(
-              doc.documentElement
-            );
-            window.sandbox
-              .stub(urlReplacements.getVariableSource(), 'get')
-              .callsFake(function (name) {
-                expect(this.replacements_).to.have.property(name);
-                return {
-                  sync: (...args) => mockMacrosBinding(name, args),
-                };
-              });
-
-            window.sandbox
-              .stub(ExpansionOptions.prototype, 'getVar')
-              .callsFake(function (name) {
-                let val = this.vars[name];
-                if (val == null || val == '') {
-                  val = '!' + name;
-                }
-                return val;
-              });
-
-            analytics = getAnalyticsTag(doc, vendor);
-            analytics.layoutCallback().then(() => {
-              config = analytics.config_;
-              done();
-            });
-
-            // Have to get service after analytics element is created
-            const variableService = variableServiceForDoc(doc);
-
-            window.sandbox
-              .stub(variableService, 'getMacros')
-              .callsFake(function () {
-                // Add all the macros in amp-analytics
-                const merged = {...this.macros_, ...elementMacros};
-
-                // Change the resolving function
-                const keys = Object.keys(merged);
-                for (let i = 0; i < keys.length; i++) {
-                  const key = keys[i];
-                  merged[key] = (...args) => mockMacrosBinding(key, args);
-                }
-                return /** @type {!JsonObject} */ (merged);
-              });
-          });
-
-          it('test requests', function* () {
-            const outputConfig = {};
-            if (!config.requests) {
-              throw new Error(
-                'Request for ' +
-                  vendor +
-                  ' not found. Please make sure you run ' +
-                  '"gulp vendor-configs" or build amp-analytics ' +
-                  'before running the test'
-              );
-            }
-            for (const name in config.requests) {
-              // Wait for event queue to clear.
-              // To prevent default triggers
-              yield macroTask();
-              analytics.handleEvent_(
-                {
-                  request: name,
-                },
-                {
-                  vars: Object.create(null),
-                }
-              );
-
-              // Reset $requestCount value after each
-              analytics.config_['vars']['requestCount'] = 0;
-
-              yield macroTask();
-              expect(requestVerifier.hasRequestSent()).to.be.true;
-              const lastUrl = requestVerifier.getLastRequestUrl();
-              const vendorData = VENDOR_REQUESTS[vendor];
-              if (!vendorData) {
-                throw new Error(
-                  'Add vendor ' + vendor + ' to vendor-requests.json'
-                );
-              }
-              const val = vendorData[name];
-              if (val == '<ignore for test>') {
-                continue;
-              }
-              if (val == null) {
-                throw new Error(
-                  'Define ' +
-                    vendor +
-                    '.' +
-                    name +
-                    ' in vendor-requests.json. Last sent out value is: ' +
-                    lastUrl
-                );
-              }
-              outputConfig[name] = lastUrl;
-              // Write this out for easy copy pasting.
-              if (!requestVerifier.verifyAndRemoveRequestUrl(val)) {
-                throw new Error(
-                  `Vendor ${vendor}, request ${name} doesn't match. ` +
-                    `Expected value ${val}, last sent out value is ${lastUrl}.`
-                );
-              }
-            }
-            writeOutput(vendor, outputConfig);
-          });
-        });
-      }
-    });
-  }
-);
-
-/**
- * Get the AmpAnalytics instance
- * @param {string} vendor
- */
-function getAnalyticsTag(doc, vendor) {
-  const el = doc.createElement('amp-analytics');
-  el.setAttribute('type', vendor);
-
-  // Overwrite transport method to use image
-  expectAsyncConsoleError(/should not overwrite vendor transport/);
-  const script = doc.createElement('script');
-  script.setAttribute('type', 'application/json');
-  script.textContent = JSON.stringify({
-    'transport': {
-      'iframe': false,
-      'image': true,
-    },
-  });
-  el.appendChild(script);
-
-  doc.body.appendChild(el);
-  el.connectedCallback();
-  const analytics = new AmpAnalytics(el);
-  analytics.createdCallback();
-  analytics.buildCallback();
-  return analytics;
-}
-
-let outputBox;
-
-function writeOutput(vendor, output) {
-  if (!outputBox) {
-    outputBox = top.document.createElement('div');
-    top.document.body.appendChild(outputBox);
-  }
-  const vendorDiv = top.document.createElement('h3');
-  vendorDiv.textContent = vendor;
-  outputBox.appendChild(vendorDiv);
-
-  const out = top.document.createElement('div');
-  out.textContent = JSON.stringify(output, null, '  ');
-  outputBox.appendChild(out);
-}
-
-/**
- * CLIENT_ID(_ga) -> _client_id(_ga)_
- * $NOT(true) -> _not(true)_
- * @param {string} macroName
- * @param {!Array<string>} argumentsList
- */
-function mockMacrosBinding(macroName, argumentsList) {
-  let params = argumentsList.filter((val) => val !== undefined).join(',');
-  if (params) {
-    params = '(' + params + ')';
-  }
-  return `_${macroName.replace('$', '').toLowerCase()}${params}_`;
-}
diff --git a/extensions/amp-analytics/0.1/test/test-vendors.js b/extensions/amp-analytics/0.1/test/test-vendors.js
index 7c7ff737dece..0b3190e672c3 100644
--- a/extensions/amp-analytics/0.1/test/test-vendors.js
+++ b/extensions/amp-analytics/0.1/test/test-vendors.js
@@ -1,5 +1,5 @@
 /**
- * Copyright 2017 The AMP HTML Authors. All Rights Reserved.
+ * Copyright 2019 The AMP HTML Authors. All Rights Reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -14,49 +14,28 @@
  * limitations under the License.
  */
 
-import {ANALYTICS_CONFIG} from '../vendors';
 import {AmpAnalytics} from '../amp-analytics';
+import {AnalyticsConfig} from '../config';
 import {ExpansionOptions, variableServiceForDoc} from '../variables';
-//import {IFRAME_TRANSPORTS} from '../iframe-transport-vendors';
+import {IFRAME_TRANSPORTS} from '../iframe-transport-vendors';
 import {
   ImagePixelVerifier,
   mockWindowInterface,
 } from '../../../../testing/test-helper';
 import {Services} from '../../../../src/services';
-//import {hasOwn} from '../../../../src/utils/object';
+import {hasOwn} from '../../../../src/utils/object';
 import {macroTask} from '../../../../testing/yield';
 
-// TODO(zhouyx@): Remove after ANALYTICS_VENDOR_SPLIT clean up
-
 /* global require: false */
 const VENDOR_REQUESTS = require('./vendor-requests.json');
-const AnalyticsConfig = {...ANALYTICS_CONFIG};
-
-// TODO(zhouyx@) Fix the "describe block" if we are going to revert the test
-// "Top-level "describe" blocks in test files have been deprecated"
-
-// describe.skip('iframe transport', () => {
-//   it('Should not contain iframe transport if not whitelisted', () => {
-//     for (const vendor in AnalyticsConfig) {
-//       const vendorEntry = AnalyticsConfig[vendor];
-//       if (
-//         hasOwn(vendorEntry, 'transport') &&
-//         hasOwn(vendorEntry.transport, 'iframe')
-//       ) {
-//         expect(vendorEntry['transport']['iframe']).to.equal(
-//           IFRAME_TRANSPORTS[vendor]
-//         );
-//       }
-//     }
-//   });
-// });
 
-describes.realWin.skip(
+describes.realWin(
   'amp-analytics',
   {
     amp: {
       extensions: ['amp-analytics'],
     },
+    mockFetch: false,
   },
   function (env) {
     let win, doc;
@@ -75,189 +54,201 @@ describes.realWin.skip(
       };
     });
 
-    function getAnalyticsTag(config, attrs) {
-      config['transport'] = {
-        xhrpost: false,
-        beacon: false,
-      };
-      config = JSON.stringify(config);
-      const el = doc.createElement('amp-analytics');
-      const script = doc.createElement('script');
-      script.textContent = config;
-      script.setAttribute('type', 'application/json');
-      el.appendChild(script);
-      for (const k in attrs) {
-        el.setAttribute(k, attrs[k]);
-      }
-
-      doc.body.appendChild(el);
-
-      el.connectedCallback();
-      const analytics = new AmpAnalytics(el);
-      analytics.createdCallback();
-      analytics.buildCallback();
-      return analytics;
-    }
-
-    /**
-     * Clears the properties in the config that should only be used in vendor
-     * configs. This is needed because we pass in all the vendor requests as
-     * inline config and iframePings/optout are not allowed to be used without
-     * AMP team's approval.
-     *
-     * @param {!JsonObject} config The inline config to update.
-     * @return {!JsonObject}
-     */
-    function clearVendorOnlyConfig(config) {
-      for (const t in config.triggers) {
-        if (config.triggers[t].iframePing) {
-          config.triggers[t].iframePing = undefined;
-        }
-      }
-      if (config.optout) {
-        config.optout = undefined;
+    describe('Should not contain iframe transport if not whitelisted', () => {
+      for (const vendor in VENDOR_REQUESTS) {
+        it('test vendor: ' + vendor, () => {
+          const el = doc.createElement('amp-analytics');
+          el.setAttribute('type', vendor);
+          doc.body.appendChild(el);
+          const analyticsConfig = new AnalyticsConfig(el);
+          return analyticsConfig.loadConfig().then((config) => {
+            if (
+              hasOwn(config, 'transport') &&
+              hasOwn(config.transport, 'iframe')
+            ) {
+              expect(config['transport']['iframe']).to.equal(
+                IFRAME_TRANSPORTS[vendor]
+              );
+            }
+          });
+        });
       }
-      return config;
-    }
+    });
 
     describe('vendor request tests', () => {
-      for (const vendor in AnalyticsConfig) {
-        if (vendor === 'default') {
-          continue;
-        }
-        const config = AnalyticsConfig[vendor];
-        if (!config.requests) {
-          delete AnalyticsConfig[vendor];
-          continue;
-        }
+      for (const vendor in VENDOR_REQUESTS) {
         describe('analytics vendor: ' + vendor, function () {
-          beforeEach(() => {
-            // Remove all the triggers to prevent unwanted requests, for instance
-            // one from a "visible" trigger. Those unwanted requests are a source
-            // of test flakiness. Especially they will alternate value of var
-            // $requestCount.
-            config.triggers = {};
+          let config;
+          let analytics;
+          beforeEach((done) => {
+            const urlReplacements = Services.urlReplacementsForDoc(
+              doc.documentElement
+            );
+            window.sandbox
+              .stub(urlReplacements.getVariableSource(), 'get')
+              .callsFake(function (name) {
+                expect(this.replacements_).to.have.property(name);
+                return {
+                  sync: (...args) => mockMacrosBinding(name, args),
+                };
+              });
+
+            window.sandbox
+              .stub(ExpansionOptions.prototype, 'getVar')
+              .callsFake(function (name) {
+                let val = this.vars[name];
+                if (val == null || val == '') {
+                  val = '!' + name;
+                }
+                return val;
+              });
+
+            analytics = getAnalyticsTag(doc, vendor);
+            analytics.layoutCallback().then(() => {
+              config = analytics.config_;
+              done();
+            });
+
+            // Have to get service after analytics element is created
+            const variableService = variableServiceForDoc(doc);
+
+            window.sandbox
+              .stub(variableService, 'getMacros')
+              .callsFake(function () {
+                // Add all the macros in amp-analytics
+                const merged = {...this.macros_, ...elementMacros};
+
+                // Change the resolving function
+                const keys = Object.keys(merged);
+                for (let i = 0; i < keys.length; i++) {
+                  const key = keys[i];
+                  merged[key] = (...args) => mockMacrosBinding(key, args);
+                }
+                return /** @type {!JsonObject} */ (merged);
+              });
           });
 
-          for (const name in config.requests) {
-            it(
-              'should produce request: ' +
-                name +
-                '. If this test fails update vendor-requests.json',
-              function* () {
-                const urlReplacements = Services.urlReplacementsForDoc(
-                  doc.documentElement
+          it('test requests', function* () {
+            const outputConfig = {};
+            if (!config.requests) {
+              throw new Error(
+                'Request for ' +
+                  vendor +
+                  ' not found. Please make sure you run ' +
+                  '"gulp vendor-configs" or build amp-analytics ' +
+                  'before running the test'
+              );
+            }
+            for (const name in config.requests) {
+              // Wait for event queue to clear.
+              // To prevent default triggers
+              yield macroTask();
+              analytics.handleEvent_(
+                {
+                  request: name,
+                },
+                {
+                  vars: Object.create(null),
+                }
+              );
+
+              // Reset $requestCount value after each
+              analytics.config_['vars']['requestCount'] = 0;
+
+              yield macroTask();
+              expect(requestVerifier.hasRequestSent()).to.be.true;
+              const lastUrl = requestVerifier.getLastRequestUrl();
+              const vendorData = VENDOR_REQUESTS[vendor];
+              if (!vendorData) {
+                throw new Error(
+                  'Add vendor ' + vendor + ' to vendor-requests.json'
                 );
-                const analytics = getAnalyticsTag(
-                  clearVendorOnlyConfig(config)
+              }
+              const val = vendorData[name];
+              if (val == '<ignore for test>') {
+                continue;
+              }
+              if (val == null) {
+                throw new Error(
+                  'Define ' +
+                    vendor +
+                    '.' +
+                    name +
+                    ' in vendor-requests.json. Last sent out value is: ' +
+                    lastUrl
                 );
-                window.sandbox
-                  .stub(urlReplacements.getVariableSource(), 'get')
-                  .callsFake(function (name) {
-                    expect(this.replacements_).to.have.property(name);
-                    const defaultValue = `_${name.toLowerCase()}_`;
-                    return {
-                      sync: () => defaultValue,
-                    };
-                  });
-
-                window.sandbox
-                  .stub(ExpansionOptions.prototype, 'getVar')
-                  .callsFake(function (name) {
-                    let val = this.vars[name];
-                    if (val == null || val == '') {
-                      val = '!' + name;
-                    }
-                    return val;
-                  });
-                analytics.createdCallback();
-                analytics.buildCallback();
-                yield analytics.layoutCallback();
-
-                // Have to get service after analytics element is created
-                const variableService = variableServiceForDoc(doc);
-
-                window.sandbox
-                  .stub(variableService, 'getMacros')
-                  .callsFake(function () {
-                    // Add all the macros in amp-analytics
-                    const merged = {...this.macros_, ...elementMacros};
-
-                    // Change the resolving function
-                    const keys = Object.keys(merged);
-                    for (let i = 0; i < keys.length; i++) {
-                      const key = keys[i];
-                      merged[key] = (opt_param, opt_param2, opt_param3) => {
-                        return `_${key.replace('$', '')}_`;
-                      };
-                    }
-                    return /** @type {!JsonObject} */ (merged);
-                  });
-
-                // Wait for event queue to clear.
-                yield macroTask();
-
-                analytics.handleEvent_(
-                  {
-                    request: name,
-                  },
-                  {
-                    vars: Object.create(null),
-                  }
+              }
+              outputConfig[name] = lastUrl;
+              // Write this out for easy copy pasting.
+              if (!requestVerifier.verifyAndRemoveRequestUrl(val)) {
+                throw new Error(
+                  `Vendor ${vendor}, request ${name} doesn't match. ` +
+                    `Expected value ${val}, last sent out value is ${lastUrl}.`
                 );
-                yield macroTask();
-                expect(requestVerifier.hasRequestSent()).to.be.true;
-                let url = requestVerifier.getLastRequestUrl();
-
-                const vendorData = VENDOR_REQUESTS[vendor];
-                if (!vendorData) {
-                  throw new Error(
-                    'Add vendor ' + vendor + ' to vendor-requests.json'
-                  );
-                }
-                const val = vendorData[name];
-                if (val == '<ignore for test>') {
-                  url = '<ignore for test>';
-                }
-                if (val == null) {
-                  throw new Error(
-                    'Define ' +
-                      vendor +
-                      '.' +
-                      name +
-                      ' in vendor-requests.json. Expected value: ' +
-                      url
-                  );
-                }
-
-                // Write this out for easy copy pasting.
-                writeOutput(vendor, name, url);
-
-                expect(url).to.equal(val);
               }
-            );
-          }
+            }
+            writeOutput(vendor, outputConfig);
+          });
         });
       }
     });
   }
 );
 
-const actualResults = {};
+/**
+ * Get the AmpAnalytics instance
+ * @param {string} vendor
+ */
+function getAnalyticsTag(doc, vendor) {
+  const el = doc.createElement('amp-analytics');
+  el.setAttribute('type', vendor);
+
+  // Overwrite transport method to use image
+  expectAsyncConsoleError(/should not overwrite vendor transport/);
+  const script = doc.createElement('script');
+  script.setAttribute('type', 'application/json');
+  script.textContent = JSON.stringify({
+    'transport': {
+      'iframe': false,
+      'image': true,
+    },
+  });
+  el.appendChild(script);
+
+  doc.body.appendChild(el);
+  el.connectedCallback();
+  const analytics = new AmpAnalytics(el);
+  analytics.createdCallback();
+  analytics.buildCallback();
+  return analytics;
+}
+
+let outputBox;
 
-function writeOutput(vendor, name, url) {
-  if (!actualResults[vendor]) {
-    actualResults[vendor] = {};
+function writeOutput(vendor, output) {
+  if (!outputBox) {
+    outputBox = top.document.createElement('div');
+    top.document.body.appendChild(outputBox);
   }
-  actualResults[vendor][name] = url;
-  const cnt = Object.keys(AnalyticsConfig[vendor]['requests']).length;
-  AnalyticsConfig[vendor].testCnt = (AnalyticsConfig[vendor].testCnt || 0) + 1;
-  if (cnt == AnalyticsConfig[vendor].testCnt) {
-    delete AnalyticsConfig[vendor];
-    if (Object.keys(AnalyticsConfig).length == 1) {
-      const out = top.document.createElement('div');
-      out.textContent = JSON.stringify(actualResults, null, '  ');
-      top.document.body.insertBefore(out, top.document.body.firstChild);
-    }
+  const vendorDiv = top.document.createElement('h3');
+  vendorDiv.textContent = vendor;
+  outputBox.appendChild(vendorDiv);
+
+  const out = top.document.createElement('div');
+  out.textContent = JSON.stringify(output, null, '  ');
+  outputBox.appendChild(out);
+}
+
+/**
+ * CLIENT_ID(_ga) -> _client_id(_ga)_
+ * $NOT(true) -> _not(true)_
+ * @param {string} macroName
+ * @param {!Array<string>} argumentsList
+ */
+function mockMacrosBinding(macroName, argumentsList) {
+  let params = argumentsList.filter((val) => val !== undefined).join(',');
+  if (params) {
+    params = '(' + params + ')';
   }
+  return `_${macroName.replace('$', '').toLowerCase()}${params}_`;
 }
diff --git a/extensions/amp-analytics/0.1/test/vendor-requests.json b/extensions/amp-analytics/0.1/test/vendor-requests.json
index 620b0a338fe9..e4de7c85905e 100644
--- a/extensions/amp-analytics/0.1/test/vendor-requests.json
+++ b/extensions/amp-analytics/0.1/test/vendor-requests.json
@@ -37,6 +37,11 @@
     "pageview": "https://hm.baidu.com/hm.gif?si=!token&nv=0&st=4&v=pixel-1.0&rnd=_timestamp_&et=0",
     "event": "https://hm.baidu.com/hm.gif?si=!token&nv=0&st=4&v=pixel-1.0&rnd=_timestamp_&ep=!category*!action*!label*!value&et=4&api=8_0"
   },
+  "blueconic": {
+    "event": "https://!tenantId/s/!pixelId.gif?",
+    "trackingIdentifier": "https://!tenantId/s/!pixelId.gif?property=!property&!property=_client_id(cid-scope-cookie-fallback-name)_!extraTrackingValues",
+    "defaultTrackingValues": "https://!tenantId/s/!pixelId.gif?property=!property&!property=_client_id(cid-scope-cookie-fallback-name)_!extraTrackingValues&sourceUrl=_source_url_&canonicalUrl=_canonical_url_&referrer=_document_referrer_&title=_title_&visitDate=_timestamp_&geoLocation=_amp_geo_&userAgent=_user_agent_"
+  },
   "browsi": {
     "host": "https://events.browsiprod.com/events/amp",
     "base": "https://events.browsiprod.com/events/amp?pk=!pubKey&sk=!siteKey&et=!type&pvid=_page_view_id_64_&aid=_ampdoc_url_&now=_timestamp_",
@@ -79,8 +84,8 @@
   },
   "comscore": {
     "host": "https://sb.scorecardresearch.com",
-    "base": "https://sb.scorecardresearch.com/b?",
-    "pageview": "https://sb.scorecardresearch.com/b?c1=2&c2=1000001&cs_ucfr=_if(_equals(_consent_state_%2Csufficient)_%2C1)__if(_equals(_consent_state_%2Cinsufficient)_%2C0)__if(_equals(_consent_state_%2C)_%2C)_&cs_amp_consent=_consent_state_&cs_pv=_page_view_id_&c12=_client_id(comScore)_&rn=_random_&c8=_title_&c7=_canonical_url_&c9=_document_referrer_&cs_c7amp=_ampdoc_url_"
+    "base": "https://sb.scorecardresearch.com/p?",
+    "pageview": "https://sb.scorecardresearch.com/p?c1=2&c2=1000001&cs_ucfr=_if(_equals(_consent_state_%2Csufficient)_%2C1)__if(_equals(_consent_state_%2Cinsufficient)_%2C0)__if(_equals(_consent_state_%2C)_%2C)_&cs_amp_consent=_consent_state_&cs_pv=_page_view_id_&c12=_client_id(comScore)_&rn=_random_&c8=_title_&c7=_canonical_url_&c9=_document_referrer_&cs_c7amp=_ampdoc_url_"
   },
   "cxense": {
     "host": "https://scomcluster.cxense.com",
diff --git a/extensions/amp-analytics/0.1/transport.js b/extensions/amp-analytics/0.1/transport.js
index 45222630d708..2de4ee2db194 100644
--- a/extensions/amp-analytics/0.1/transport.js
+++ b/extensions/amp-analytics/0.1/transport.js
@@ -142,7 +142,7 @@ export class Transport {
 
   /**
    * amp-analytics will create an iframe for vendors in
-   * extensions/amp-analytics/0.1/vendors.js who have transport/iframe defined.
+   * extensions/amp-analytics/0.1/vendors/* who have transport/iframe defined.
    * This is limited to MRC-accreddited vendors. The frame is removed if the
    * user navigates/swipes away from the page, and is recreated if the user
    * navigates back to the page.
diff --git a/extensions/amp-analytics/0.1/vendors/blueconic.json b/extensions/amp-analytics/0.1/vendors/blueconic.json
new file mode 100644
index 000000000000..a4546c1808f9
--- /dev/null
+++ b/extensions/amp-analytics/0.1/vendors/blueconic.json
@@ -0,0 +1,10 @@
+{
+  "requests": {
+    "event": "https://${tenantId}/s/${pixelId}.gif?",
+    "trackingIdentifier": "${event}property=${property}&${property}=${clientId(cid-scope-cookie-fallback-name)}${extraTrackingValues}",
+    "defaultTrackingValues": "${trackingIdentifier}&sourceUrl=${sourceUrl}&canonicalUrl=${canonicalUrl}&referrer=${documentReferrer}&title=${title}&visitDate=${timestamp}&geoLocation=${ampGeo}&userAgent=${userAgent}"
+  },
+  "vars": {
+    "extraTrackingValues": ""
+  }
+}
diff --git a/extensions/amp-analytics/0.1/vendors/comscore.json b/extensions/amp-analytics/0.1/vendors/comscore.json
index 9ef372ab8aff..64c590aa7928 100644
--- a/extensions/amp-analytics/0.1/vendors/comscore.json
+++ b/extensions/amp-analytics/0.1/vendors/comscore.json
@@ -4,7 +4,7 @@
   },
   "requests": {
     "host": "https://sb.scorecardresearch.com",
-    "base": "${host}/b?",
+    "base": "${host}/p?",
     "pageview": "${base}c1=2&c2=${c2}&cs_ucfr=$IF($EQUALS(${consentState}, sufficient), 1)$IF($EQUALS(${consentState}, insufficient), 0)$IF($EQUALS(${consentState}, ), )&cs_amp_consent=${consentState}&cs_pv=${pageViewId}&c12=${clientId(comScore)}&rn=${random}&c8=${title}&c7=${canonicalUrl}&c9=${documentReferrer}&cs_c7amp=${ampdocUrl}"
   },
   "triggers": {
diff --git a/extensions/amp-animation/0.1/parsers/css-expr-ast.js b/extensions/amp-animation/0.1/parsers/css-expr-ast.js
index c218077e71f1..4cf19691c7e7 100644
--- a/extensions/amp-animation/0.1/parsers/css-expr-ast.js
+++ b/extensions/amp-animation/0.1/parsers/css-expr-ast.js
@@ -17,7 +17,7 @@
 const FINAL_URL_RE = /^(data|https)\:/i;
 const DEG_TO_RAD = (2 * Math.PI) / 360;
 const GRAD_TO_RAD = Math.PI / 200;
-const VAR_CSS_RE = /(calc|min|max|clamp|var|url|rand|index|width|height|num|length)\(/i;
+const VAR_CSS_RE = /\b(calc|min|max|clamp|var|url|rand|index|width|height|num|length|x|y)\(/i;
 const NORM_CSS_RE = /\d(%|em|rem|vw|vh|vmin|vmax|s|deg|grad)/i;
 const INFINITY_RE = /^(infinity|infinite)$/i;
 const BOX_DIMENSIONS = ['h', 'w', 'h', 'w'];
@@ -87,18 +87,18 @@ export class CssContext {
   getViewportSize() {}
 
   /**
-   * Returns the current element's size.
-   * @return {!{width: number, height: number}}
+   * Returns the current element's rectangle.
+   * @return {!../../../../src/layout-rect.LayoutRectDef}
    */
-  getCurrentElementSize() {}
+  getCurrentElementRect() {}
 
   /**
-   * Returns the specified element's size.
+   * Returns the specified element's rectangle.
    * @param {string} unusedSelector
    * @param {?string} unusedSelectionMethod
-   * @return {!{width: number, height: number}}
+   * @return {!../../../../src/layout-rect.LayoutRectDef}
    */
-  getElementSize(unusedSelector, unusedSelectionMethod) {}
+  getElementRect(unusedSelector, unusedSelectionMethod) {}
 
   /**
    * Returns the dimension: "w" for width or "h" for height.
@@ -487,8 +487,8 @@ export class CssLengthNode extends CssNumericNode {
   /** @override */
   calcPercent(percent, context) {
     const dim = context.getDimension();
-    const size = context.getCurrentElementSize();
-    const side = getDimSide(dim, size);
+    const size = context.getCurrentElementRect();
+    const side = getRectField(dim, size);
     return new CssLengthNode((side * percent) / 100, 'px');
   }
 }
@@ -847,16 +847,16 @@ export class CssTranslateNode extends CssFuncNode {
 /**
  * AMP-specific `width()` and `height()` functions.
  */
-export class CssDimSizeNode extends CssNode {
+export class CssRectNode extends CssNode {
   /**
-   * @param {string} dim
+   * @param {string} field x, y, width or height
    * @param {?string=} opt_selector
    * @param {?string=} opt_selectionMethod Either `undefined` or "closest".
    */
-  constructor(dim, opt_selector, opt_selectionMethod) {
+  constructor(field, opt_selector, opt_selectionMethod) {
     super();
     /** @const @private */
-    this.dim_ = dim;
+    this.field_ = field;
     /** @const @private */
     this.selector_ = opt_selector || null;
     /** @const @private */
@@ -875,10 +875,10 @@ export class CssDimSizeNode extends CssNode {
 
   /** @override */
   calc(context) {
-    const size = this.selector_
-      ? context.getElementSize(this.selector_, this.selectionMethod_)
-      : context.getCurrentElementSize();
-    return new CssLengthNode(getDimSide(this.dim_, size), 'px');
+    const rect = this.selector_
+      ? context.getElementRect(this.selector_, this.selectionMethod_)
+      : context.getCurrentElementRect();
+    return new CssLengthNode(getRectField(this.field_, rect), 'px');
   }
 }
 
@@ -1381,12 +1381,18 @@ function noCss() {
 }
 
 /**
- * @param {?string} dim
- * @param {!{width: number, height: number}} size
+ * @param {?string} field
+ * @param {!../../../../src/layout-rect.LayoutRectDef} rect
  * @return {number}
  */
-function getDimSide(dim, size) {
-  return dim == 'w' ? size.width : dim == 'h' ? size.height : 0;
+function getRectField(field, rect) {
+  if (field == 'w') {
+    return rect.width;
+  }
+  if (field == 'h') {
+    return rect.height;
+  }
+  return rect[field] ?? 0;
 }
 
 /**
diff --git a/extensions/amp-animation/0.1/parsers/css-expr-impl.jison b/extensions/amp-animation/0.1/parsers/css-expr-impl.jison
index 97ec6d4bd85b..78fab4e5c169 100644
--- a/extensions/amp-animation/0.1/parsers/css-expr-impl.jison
+++ b/extensions/amp-animation/0.1/parsers/css-expr-impl.jison
@@ -91,6 +91,8 @@ ident     \-?[a-zA-Z_][\-a-zA-Z0-9_]*
 {C}{I}{R}{C}{L}{E}\(                return 'CIRCLE_START'
 {E}{L}{L}{I}{P}{S}{E}\(             return 'ELLIPSE_START'
 {P}{O}{L}{Y}{G}{O}{N}\(             return 'POLYGON_START'
+{X}\(                               return 'X_START'
+{Y}\(                               return 'Y_START'
 {ident}\(                           return 'FUNCTION_START'
 {ident}                             return 'IDENT'
 \-\-{ident}                         return 'VAR_NAME';
@@ -260,7 +262,7 @@ function:
       {$$ = $1;}
   | translate_function
       {$$ = $1;}
-  | dim_function
+  | rect_function
       {$$ = $1;}
   | num_function
       {$$ = $1;}
@@ -457,25 +459,37 @@ polygon_function:
 
 
 /**
- * AMP-specific `width()` and `height()` functions:
+ * AMP-specific `width()`, `height()`, `x()` and `y()` functions:
  * - `width(".selector")`
  * - `height(".selector")`
  * - `width(closest(".selector"))`
  * - `height(closest(".selector"))`
  */
-dim_function:
+rect_function:
     WIDTH_START ')'
-      {$$ = new ast.CssDimSizeNode('w');}
+      {$$ = new ast.CssRectNode('w');}
   | HEIGHT_START ')'
-      {$$ = new ast.CssDimSizeNode('h');}
+      {$$ = new ast.CssRectNode('h');}
+  | X_START ')'
+      {$$ = new ast.CssRectNode('x');}
+  | Y_START ')'
+      {$$ = new ast.CssRectNode('y');}
   | WIDTH_START STRING ')'
-      {$$ = new ast.CssDimSizeNode('w', $2.slice(1, -1));}
+      {$$ = new ast.CssRectNode('w', $2.slice(1, -1));}
   | HEIGHT_START STRING ')'
-      {$$ = new ast.CssDimSizeNode('h', $2.slice(1, -1));}
+      {$$ = new ast.CssRectNode('h', $2.slice(1, -1));}
+  | X_START STRING ')'
+      {$$ = new ast.CssRectNode('x', $2.slice(1, -1));}
+  | Y_START STRING ')'
+      {$$ = new ast.CssRectNode('y', $2.slice(1, -1));}
   | WIDTH_START CLOSEST_START STRING ')' ')'
-      {$$ = new ast.CssDimSizeNode('w', $3.slice(1, -1), 'closest');}
+      {$$ = new ast.CssRectNode('w', $3.slice(1, -1), 'closest');}
   | HEIGHT_START CLOSEST_START STRING ')' ')'
-      {$$ = new ast.CssDimSizeNode('h', $3.slice(1, -1), 'closest');}
+      {$$ = new ast.CssRectNode('h', $3.slice(1, -1), 'closest');}
+  | X_START CLOSEST_START STRING ')' ')'
+      {$$ = new ast.CssRectNode('x', $3.slice(1, -1), 'closest');}
+  | Y_START CLOSEST_START STRING ')' ')'
+      {$$ = new ast.CssRectNode('y', $3.slice(1, -1), 'closest');}
   ;
 
 
diff --git a/extensions/amp-animation/0.1/test/test-css-expr-parser.js b/extensions/amp-animation/0.1/test/test-css-expr-parser.js
index 6bfdceb18f2f..240b57d6ef61 100644
--- a/extensions/amp-animation/0.1/test/test-css-expr-parser.js
+++ b/extensions/amp-animation/0.1/test/test-css-expr-parser.js
@@ -57,9 +57,9 @@ describes.sandboxed('CSS parse', {}, () => {
         `<${pseudoArray(n.args_, n.dimensions_)}>`
       );
     }
-    if (n instanceof ast.CssDimSizeNode) {
+    if (n instanceof ast.CssRectNode) {
       return (
-        `DIM<${n.dim_}` +
+        `RECT<${n.field_}` +
         `, ${n.selector_ ? '"' + n.selector_ + '"' : null}` +
         `, ${n.selectionMethod_}>`
       );
@@ -301,24 +301,37 @@ describes.sandboxed('CSS parse', {}, () => {
     ).to.equal('CON<A B>');
   });
 
-  it('should parse a dimension function', () => {
+  it('should parse a rect function', () => {
     // Current.
-    expect(parsePseudo('width()')).to.equal('DIM<w, null, null>');
-    expect(parsePseudo('height()')).to.equal('DIM<h, null, null>');
+    expect(parsePseudo('width()')).to.equal('RECT<w, null, null>');
+    expect(parsePseudo('height()')).to.equal('RECT<h, null, null>');
+    expect(parsePseudo('x()')).to.equal('RECT<x, null, null>');
+    expect(parsePseudo('y()')).to.equal('RECT<y, null, null>');
 
     // Query.
-    expect(parsePseudo('width(".sel")')).to.equal('DIM<w, ".sel", null>');
+    expect(parsePseudo('width(".sel")')).to.equal('RECT<w, ".sel", null>');
     expect(parsePseudo('WIDTH(".sel > div")')).to.equal(
-      'DIM<w, ".sel > div", null>'
+      'RECT<w, ".sel > div", null>'
     );
-    expect(parsePseudo('height(".sel")')).to.equal('DIM<h, ".sel", null>');
+    expect(parsePseudo('height(".sel")')).to.equal('RECT<h, ".sel", null>');
+    expect(parsePseudo('x(".sel")')).to.equal('RECT<x, ".sel", null>');
+    expect(parsePseudo('x(".sel > div")')).to.equal(
+      'RECT<x, ".sel > div", null>'
+    );
+    expect(parsePseudo('y(".sel")')).to.equal('RECT<y, ".sel", null>');
 
     // Closest.
     expect(parsePseudo('width(closest(".sel"))')).to.equal(
-      'DIM<w, ".sel", closest>'
+      'RECT<w, ".sel", closest>'
     );
     expect(parsePseudo('height(closest(".sel"))')).to.equal(
-      'DIM<h, ".sel", closest>'
+      'RECT<h, ".sel", closest>'
+    );
+    expect(parsePseudo('x(closest(".sel"))')).to.equal(
+      'RECT<x, ".sel", closest>'
+    );
+    expect(parsePseudo('y(closest(".sel"))')).to.equal(
+      'RECT<y, ".sel", closest>'
     );
   });
 
diff --git a/extensions/amp-animation/0.1/test/test-css-expr-resolve-calc.js b/extensions/amp-animation/0.1/test/test-css-expr-resolve-calc.js
index 84bf8f8165d4..2a74e721ee55 100644
--- a/extensions/amp-animation/0.1/test/test-css-expr-resolve-calc.js
+++ b/extensions/amp-animation/0.1/test/test-css-expr-resolve-calc.js
@@ -179,7 +179,7 @@ describes.sandboxed('CSS resolve calc', {}, (env) => {
     it('should resolve left as percent', () => {
       contextMock.expects('getDimension').returns('w');
       contextMock
-        .expects('getCurrentElementSize')
+        .expects('getCurrentElementRect')
         .returns({width: 110, height: 220})
         .once();
       const node = new ast.CssCalcSumNode(
@@ -196,7 +196,7 @@ describes.sandboxed('CSS resolve calc', {}, (env) => {
     it('should resolve right as percent', () => {
       contextMock.expects('getDimension').returns('h');
       contextMock
-        .expects('getCurrentElementSize')
+        .expects('getCurrentElementRect')
         .returns({width: 110, height: 220})
         .once();
       const node = new ast.CssCalcSumNode(
@@ -214,7 +214,7 @@ describes.sandboxed('CSS resolve calc', {}, (env) => {
       contextMock.expects('getCurrentFontSize').returns(2).once();
       contextMock.expects('getDimension').returns('h');
       contextMock
-        .expects('getCurrentElementSize')
+        .expects('getCurrentElementRect')
         .returns({width: 110, height: 220})
         .once();
       const node = new ast.CssCalcSumNode(
@@ -230,12 +230,12 @@ describes.sandboxed('CSS resolve calc', {}, (env) => {
 
     it('should resolve with dimension function', () => {
       contextMock
-        .expects('getElementSize')
+        .expects('getElementRect')
         .returns({width: 111, height: 222})
         .twice();
       const node = new ast.CssCalcSumNode(
-        new ast.CssDimSizeNode('w', '.sel'),
-        new ast.CssDimSizeNode('h', '.sel'),
+        new ast.CssRectNode('w', '.sel'),
+        new ast.CssRectNode('h', '.sel'),
         '+'
       );
       // 111px + 222px = 333px
@@ -542,7 +542,7 @@ describes.sandboxed('CSS resolve calc', {}, (env) => {
       () => {
         contextMock.expects('getDimension').returns('w').atLeast(1);
         contextMock
-          .expects('getCurrentElementSize')
+          .expects('getCurrentElementRect')
           .returns({width: 110, height: 220})
           .atLeast(1);
         return [
@@ -561,7 +561,7 @@ describes.sandboxed('CSS resolve calc', {}, (env) => {
       () => {
         contextMock.expects('getDimension').returns('h').atLeast(1);
         contextMock
-          .expects('getCurrentElementSize')
+          .expects('getCurrentElementRect')
           .returns({width: 110, height: 220})
           .atLeast(1);
         return [new ast.CssLengthNode(25, 'px'), new ast.CssPercentNode(10)];
@@ -577,7 +577,7 @@ describes.sandboxed('CSS resolve calc', {}, (env) => {
         contextMock.expects('getCurrentFontSize').returns(2).atLeast(1);
         contextMock.expects('getDimension').returns('h').atLeast(1);
         contextMock
-          .expects('getCurrentElementSize')
+          .expects('getCurrentElementRect')
           .returns({width: 110, height: 220})
           .atLeast(1);
         return [new ast.CssLengthNode(10, 'em'), new ast.CssPercentNode(10)];
@@ -591,12 +591,12 @@ describes.sandboxed('CSS resolve calc', {}, (env) => {
       'should resolve with dimension function',
       () => {
         contextMock
-          .expects('getElementSize')
+          .expects('getElementRect')
           .returns({width: 111, height: 222})
           .atLeast(1);
         return [
-          new ast.CssDimSizeNode('w', '.sel'),
-          new ast.CssDimSizeNode('h', '.sel'),
+          new ast.CssRectNode('w', '.sel'),
+          new ast.CssRectNode('h', '.sel'),
         ];
       },
       // No CSS.
@@ -610,7 +610,7 @@ describes.sandboxed('CSS resolve calc', {}, (env) => {
       () => {
         contextMock.expects('getDimension').returns('w').atLeast(1);
         contextMock
-          .expects('getCurrentElementSize')
+          .expects('getCurrentElementRect')
           .returns({width: 110, height: 220})
           .atLeast(1);
         contextMock.expects('getCurrentFontSize').returns(1).atLeast(1);
@@ -631,7 +631,7 @@ describes.sandboxed('CSS resolve calc', {}, (env) => {
       () => {
         contextMock.expects('getDimension').returns('w').atLeast(1);
         contextMock
-          .expects('getCurrentElementSize')
+          .expects('getCurrentElementRect')
           .returns({width: 110, height: 220})
           .atLeast(1);
         contextMock.expects('getCurrentFontSize').returns(1).atLeast(1);
diff --git a/extensions/amp-animation/0.1/test/test-css-expr-resolve.js b/extensions/amp-animation/0.1/test/test-css-expr-resolve.js
index c7ec0f035f25..c1ff45ec14eb 100644
--- a/extensions/amp-animation/0.1/test/test-css-expr-resolve.js
+++ b/extensions/amp-animation/0.1/test/test-css-expr-resolve.js
@@ -144,7 +144,7 @@ describes.sandboxed('CSS resolve', {}, (env) => {
   it('should resolve a percent node w/dimension', () => {
     contextMock.expects('getDimension').returns('w').twice();
     contextMock
-      .expects('getCurrentElementSize')
+      .expects('getCurrentElementRect')
       .returns({width: 110, height: 220});
     expect(ast.isVarCss('11.5%', false)).to.be.false;
     const node = new ast.CssPercentNode(11.5);
@@ -359,7 +359,7 @@ describes.sandboxed('CSS resolve', {}, (env) => {
     it('should resolve a percent-length in w-direction', () => {
       contextMock.expects('getDimension').returns('w');
       contextMock
-        .expects('getCurrentElementSize')
+        .expects('getCurrentElementRect')
         .returns({width: 110, height: 220})
         .once();
       const node = new ast.CssLengthNode(11.5, 'px');
@@ -370,7 +370,7 @@ describes.sandboxed('CSS resolve', {}, (env) => {
     it('should resolve a percent-length in h-direction', () => {
       contextMock.expects('getDimension').returns('h');
       contextMock
-        .expects('getCurrentElementSize')
+        .expects('getCurrentElementRect')
         .returns({width: 110, height: 220})
         .once();
       const node = new ast.CssLengthNode(11.5, 'px');
@@ -380,7 +380,7 @@ describes.sandboxed('CSS resolve', {}, (env) => {
 
     it('should resolve a percent-length in unknown direction', () => {
       contextMock
-        .expects('getCurrentElementSize')
+        .expects('getCurrentElementRect')
         .returns({width: 110, height: 220})
         .once();
       const node = new ast.CssLengthNode(11.5, 'px');
@@ -520,7 +520,7 @@ describes.sandboxed('CSS resolve', {}, (env) => {
       contextMock.expects('getDimension').returns('w').atLeast(1);
       contextMock.expects('getCurrentFontSize').returns(10).atLeast(1);
       contextMock
-        .expects('getCurrentElementSize')
+        .expects('getCurrentElementRect')
         .returns({width: 110, height: 220})
         .atLeast(1);
       const node = new ast.CssFuncNode('xyz', [
@@ -688,63 +688,97 @@ describes.sandboxed('CSS resolve', {}, (env) => {
   });
 
   describe('dimension', () => {
-    let sizes;
+    let rects;
 
     beforeEach(() => {
-      sizes = {
-        'null(.class)': {width: 111, height: 222},
-        'closest(.class > div)': {width: 112, height: 224},
+      rects = {
+        'null(.class)': {x: 10, y: 20, width: 111, height: 222},
+        'closest(.class > div)': {x: 11, y: 12, width: 112, height: 224},
       };
-      context.getCurrentElementSize = function () {
-        return {width: 110, height: 220};
+      context.getCurrentElementRect = function () {
+        return {x: 13, y: 14, width: 110, height: 220};
       };
-      context.getElementSize = function (selector, selectionMethod) {
-        return sizes[`${selectionMethod}(${selector})`];
+      context.getElementRect = function (selector, selectionMethod) {
+        return rects[`${selectionMethod}(${selector})`];
       };
     });
 
     it('should always consider as non-const', () => {
       expect(ast.isVarCss('width()', false)).to.be.true;
       expect(ast.isVarCss('height()', false)).to.be.true;
+      expect(ast.isVarCss('x()', false)).to.be.true;
+      expect(ast.isVarCss('y()', false)).to.be.true;
       expect(ast.isVarCss('width("")')).to.be.true;
       expect(ast.isVarCss('height("")')).to.be.true;
+      expect(ast.isVarCss('x("")')).to.be.true;
+      expect(ast.isVarCss('y("")')).to.be.true;
     });
 
     it('should be always a non-const and no css', () => {
-      const node = new ast.CssDimSizeNode('?');
+      const node = new ast.CssRectNode('?');
       expect(node.isConst()).to.be.false;
       expect(() => node.css()).to.throw(/no css/);
     });
 
     it('should resolve width on the current node', () => {
-      const node = new ast.CssDimSizeNode('w');
+      const node = new ast.CssRectNode('w');
       expect(node.calc(context).css()).to.equal('110px');
     });
 
     it('should resolve height on the current node', () => {
-      const node = new ast.CssDimSizeNode('h');
+      const node = new ast.CssRectNode('h');
       expect(node.calc(context).css()).to.equal('220px');
     });
 
     it('should resolve width on the selected node', () => {
-      const node = new ast.CssDimSizeNode('w', '.class');
+      const node = new ast.CssRectNode('w', '.class');
       expect(node.calc(context).css()).to.equal('111px');
     });
 
     it('should resolve height on the selected node', () => {
-      const node = new ast.CssDimSizeNode('h', '.class');
+      const node = new ast.CssRectNode('h', '.class');
       expect(node.calc(context).css()).to.equal('222px');
     });
 
     it('should resolve width on the selected closest node', () => {
-      const node = new ast.CssDimSizeNode('w', '.class > div', 'closest');
+      const node = new ast.CssRectNode('w', '.class > div', 'closest');
       expect(node.calc(context).css()).to.equal('112px');
     });
 
     it('should resolve height on the selected closest node', () => {
-      const node = new ast.CssDimSizeNode('h', '.class > div', 'closest');
+      const node = new ast.CssRectNode('h', '.class > div', 'closest');
       expect(node.calc(context).css()).to.equal('224px');
     });
+
+    it('should resolve x coord on the current node', () => {
+      const node = new ast.CssRectNode('x');
+      expect(node.calc(context).css()).to.equal('13px');
+    });
+
+    it('should resolve y coord on the current node', () => {
+      const node = new ast.CssRectNode('y');
+      expect(node.calc(context).css()).to.equal('14px');
+    });
+
+    it('should resolve x coord on the selected node', () => {
+      const node = new ast.CssRectNode('x', '.class');
+      expect(node.calc(context).css()).to.equal('10px');
+    });
+
+    it('should resolve y coord on the selected node', () => {
+      const node = new ast.CssRectNode('y', '.class');
+      expect(node.calc(context).css()).to.equal('20px');
+    });
+
+    it('should resolve x coord on the selected closest node', () => {
+      const node = new ast.CssRectNode('x', '.class > div', 'closest');
+      expect(node.calc(context).css()).to.equal('11px');
+    });
+
+    it('should resolve y coord on the selected closest node', () => {
+      const node = new ast.CssRectNode('y', '.class > div', 'closest');
+      expect(node.calc(context).css()).to.equal('12px');
+    });
   });
 
   describe('num-convert', () => {
@@ -791,7 +825,7 @@ describes.sandboxed('CSS resolve', {}, (env) => {
 
       contextMock.expects('getDimension').returns('w').atLeast(1);
       contextMock
-        .expects('getCurrentElementSize')
+        .expects('getCurrentElementRect')
         .returns({width: 110, height: 220})
         .atLeast(1);
       expect(resolvedCss(node, normalize)).to.equal('11');
@@ -893,7 +927,7 @@ describes.sandboxed('CSS resolve', {}, (env) => {
 
       contextMock.expects('getDimension').returns('w').atLeast(1);
       contextMock
-        .expects('getCurrentElementSize')
+        .expects('getCurrentElementRect')
         .returns({width: 110, height: 220})
         .atLeast(1);
       expect(resolvedCss(node, normalize)).to.equal('13.75px');
@@ -1051,7 +1085,7 @@ describes.sandboxed('CSS resolve', {}, (env) => {
     it('should resolve a var node and normalize', () => {
       contextMock.expects('getDimension').returns('w').atLeast(1);
       contextMock
-        .expects('getCurrentElementSize')
+        .expects('getCurrentElementRect')
         .returns({width: 110, height: 220})
         .atLeast(1);
       contextMock
diff --git a/extensions/amp-animation/0.1/test/test-web-animations.js b/extensions/amp-animation/0.1/test/test-web-animations.js
index 1ed0490009c4..a85b72491577 100644
--- a/extensions/amp-animation/0.1/test/test-web-animations.js
+++ b/extensions/amp-animation/0.1/test/test-web-animations.js
@@ -1548,13 +1548,13 @@ describes.realWin('MeasureScanner', {amp: 1}, (env) => {
       target1.style.width = '11px';
       target1.style.height = '12px';
       allowConsoleError(() => {
-        expect(() => css.getCurrentElementSize()).to.throw(
+        expect(() => css.getCurrentElementRect()).to.throw(
           /target is specified/
         );
       });
       expect(
-        css.withTarget(target1, 0, () => css.getCurrentElementSize())
-      ).to.deep.equal({width: 11, height: 12});
+        css.withTarget(target1, 0, () => css.getCurrentElementRect())
+      ).to.include({width: 11, height: 12});
     });
 
     it('should resolve the selected element size', () => {
@@ -1565,23 +1565,65 @@ describes.realWin('MeasureScanner', {amp: 1}, (env) => {
       target1.appendChild(child);
 
       // Normal selectors search whole DOM and don't need context.
-      expect(css.getElementSize('#target1', null)).to.deep.equal({
+      expect(css.getElementRect('#target1', null)).to.include({
         width: 11,
         height: 12,
       });
       expect(
-        css.withTarget(target2, 0, () => css.getElementSize('#target1', null))
-      ).to.deep.equal({width: 11, height: 12});
+        css.withTarget(target2, 0, () => css.getElementRect('#target1', null))
+      ).to.include({width: 11, height: 12});
 
       // Closest selectors always need a context node.
       allowConsoleError(() => {
-        expect(() => css.getElementSize('#target1', 'closest')).to.throw(
+        expect(() => css.getElementRect('#target1', 'closest')).to.throw(
           /target is specified/
         );
       });
       expect(
-        css.withTarget(child, 0, () => css.getElementSize('.parent', 'closest'))
-      ).to.deep.equal({width: 11, height: 12});
+        css.withTarget(child, 0, () => css.getElementRect('.parent', 'closest'))
+      ).to.include({width: 11, height: 12});
+    });
+
+    it("should resolve current element's position", () => {
+      target1.style.position = 'absolute';
+      target1.style.left = '11px';
+      target1.style.top = '12px';
+      allowConsoleError(() => {
+        expect(() => css.getCurrentElementRect()).to.throw(
+          /target is specified/
+        );
+      });
+      expect(
+        css.withTarget(target1, 0, () => css.getCurrentElementRect())
+      ).to.include({x: 11, y: 12});
+    });
+
+    it("should resolve the selected element's position", () => {
+      target1.style.position = 'absolute';
+      target1.style.left = '11px';
+      target1.style.top = '12px';
+      target1.classList.add('parent');
+      const child = target1.ownerDocument.createElement('div');
+      target1.appendChild(child);
+
+      // Normal selectors search whole DOM and don't need context.
+      expect(css.getElementRect('#target1', null)).to.include({
+        x: 11,
+        y: 12,
+      });
+      expect(
+        css.withTarget(target2, 0, () => css.getElementRect('#target1', null))
+      ).to.include({x: 11, y: 12});
+
+      // Closest selectors always need a context node.
+      allowConsoleError(() => {
+        expect(() => css.getElementRect('#target1', 'closest')).to.throw(
+          /target is specified/
+        );
+      });
+      expect(
+        css.withTarget(child, 0, () => css.getElementRect('.parent', 'closest'))
+      ).to.include({x: 11, y: 12});
     });
 
     it('should resolve a valid URL', () => {
@@ -1805,17 +1847,236 @@ describes.realWin('MeasureScanner (scoped)', {amp: 1}, (env) => {
     const css = builder.css_;
 
     expect(() =>
-      css.withTarget(target1, 0, () => css.getElementSize('.parent', 'closest'))
+      css.withTarget(target1, 0, () => css.getElementRect('.parent', 'closest'))
     ).to.not.throw();
 
     allowConsoleError(() => {
       expect(() =>
         css.withTarget(target2, 0, () =>
-          css.getElementSize('.parent', 'closest')
+          css.getElementRect('.parent', 'closest')
         )
       ).to.throw(/Element not found/);
     });
   });
+
+  it("should not resolve viewport size as scope element's size", () => {
+    const scope = html`<div></div>`;
+
+    scope.style.width = '200px';
+    scope.style.height = '300px';
+
+    env.win.document.body.appendChild(scope);
+
+    const builder = new Builder(
+      env.win,
+      env.win.document,
+      'https://acme.org/',
+      /* vsync */ null,
+      /* owners */ null,
+      {scope, scaleByScope: false}
+    );
+
+    const css = builder.css_;
+
+    const size = css.getViewportSize();
+    expect(size.width).to.equal(env.win.innerWidth);
+    expect(size.height).to.equal(env.win.innerHeight);
+
+    // cached:
+    expect(css.getViewportSize()).to.equal(size);
+  });
+
+  it("should resolve viewport size as scope element's size", () => {
+    const scope = html`<div></div>`;
+
+    scope.style.width = '200px';
+    scope.style.height = '300px';
+
+    env.win.document.body.appendChild(scope);
+
+    const builder = new Builder(
+      env.win,
+      env.win.document,
+      'https://acme.org/',
+      /* vsync */ null,
+      /* owners */ null,
+      {scope, scaleByScope: true}
+    );
+
+    const css = builder.css_;
+
+    const size = css.getViewportSize();
+    expect(size.width).to.equal(200);
+    expect(size.height).to.equal(300);
+
+    // cached:
+    expect(css.getViewportSize()).to.equal(size);
+  });
+
+  it('should resolve x and y relative to scope', () => {
+    const scope = html`<div>
+      <div id="target1" ref="target1"></div>
+      <div id="target2" ref="target2"></div>
+    </div>`;
+
+    const {target1, target2} = htmlRefs(scope);
+
+    scope.style.position = 'absolute';
+    scope.style.left = '10px';
+    scope.style.top = '20px';
+
+    scope.style.width = '1000px';
+    scope.style.height = '1000px';
+
+    target1.style.position = 'absolute';
+    target1.style.left = '40px';
+    target1.style.top = '30px';
+
+    target2.style.position = 'absolute';
+    target2.style.left = '30px';
+    target2.style.top = '20px';
+
+    env.win.document.body.appendChild(scope);
+
+    const builder = new Builder(
+      env.win,
+      env.win.document,
+      'https://acme.org/',
+      /* vsync */ null,
+      /* owners */ null,
+      {scope, scaleByScope: true}
+    );
+
+    const css = builder.css_;
+
+    const pos1 = css.getElementRect('#target1', null);
+    expect(pos1.x).to.equal(40);
+    expect(pos1.y).to.equal(30);
+
+    const pos2 = css.getElementRect('#target2', null);
+    expect(pos2.x).to.equal(30);
+    expect(pos2.y).to.equal(20);
+  });
+
+  it('should resolve dimensions and size rescaled relative to scope', () => {
+    const scope = html`<div>
+      <div id="target1" ref="target1"></div>
+      <div id="target2" ref="target2"></div>
+    </div>`;
+
+    const {target1, target2} = htmlRefs(scope);
+
+    scope.style.position = 'absolute';
+    scope.style.top = '20px';
+    scope.style.left = '10px';
+
+    scope.style.width = '1000px';
+    scope.style.height = '1000px';
+
+    scope.style.transform = 'scale(0.5)';
+
+    target1.style.position = 'absolute';
+    target1.style.left = '40px';
+    target1.style.top = '30px';
+    target1.style.width = '200px';
+    target1.style.height = '100px';
+
+    target2.style.position = 'absolute';
+    target2.style.left = '30px';
+    target2.style.top = '20px';
+    target2.style.width = '300px';
+    target2.style.height = '200px';
+
+    env.win.document.body.appendChild(scope);
+
+    const builder = new Builder(
+      env.win,
+      env.win.document,
+      'https://acme.org/',
+      /* vsync */ null,
+      /* owners */ null,
+      {scope, scaleByScope: true}
+    );
+
+    const css = builder.css_;
+
+    const pos1 = css.getElementRect('#target1', null);
+    expect(pos1.x).to.equal(40);
+    expect(pos1.y).to.equal(30);
+
+    const size1 = css.getElementRect('#target1', null);
+    expect(size1.width).to.equal(200);
+    expect(size1.height).to.equal(100);
+
+    const pos2 = css.getElementRect('#target2', null);
+    expect(pos2.x).to.equal(30);
+    expect(pos2.y).to.equal(20);
+
+    const size2 = css.getElementRect('#target2', null);
+    expect(size2.width).to.equal(300);
+    expect(size2.height).to.equal(200);
+  });
+
+  it('should resolve dimensions and size not rescaled relative to scope', () => {
+    const scope = html`<div>
+      <div id="target1" ref="target1"></div>
+      <div id="target2" ref="target2"></div>
+    </div>`;
+
+    const {target1, target2} = htmlRefs(scope);
+
+    scope.style.position = 'absolute';
+    scope.style.top = '20px';
+    scope.style.left = '10px';
+
+    scope.style.width = '1000px';
+    scope.style.height = '1000px';
+
+    scope.style.transform = 'scale(0.5)';
+
+    target1.style.position = 'absolute';
+    target1.style.left = '40px';
+    target1.style.top = '30px';
+    target1.style.width = '200px';
+    target1.style.height = '100px';
+
+    target2.style.position = 'absolute';
+    target2.style.left = '30px';
+    target2.style.top = '20px';
+    target2.style.width = '300px';
+    target2.style.height = '200px';
+
+    env.win.document.body.appendChild(scope);
+
+    const builder = new Builder(
+      env.win,
+      env.win.document,
+      'https://acme.org/',
+      /* vsync */ null,
+      /* owners */ null,
+      {scope, scaleByScope: false}
+    );
+
+    const css = builder.css_;
+
+    const pos1 = css.getElementRect('#target1', null);
+    const rect1 = target1.getBoundingClientRect();
+    expect(pos1.x).to.equal(rect1.x);
+    expect(pos1.y).to.equal(rect1.y);
+
+    const size1 = css.getElementRect('#target1', null);
+    expect(size1.width).to.equal(200 * 0.5);
+    expect(size1.height).to.equal(100 * 0.5);
+
+    const pos2 = css.getElementRect('#target2', null);
+    const rect2 = target2.getBoundingClientRect();
+    expect(pos2.x).to.equal(rect2.x);
+    expect(pos2.y).to.equal(rect2.y);
+
+    const size2 = css.getElementRect('#target2', null);
+    expect(size2.width).to.equal(300 * 0.5);
+    expect(size2.height).to.equal(200 * 0.5);
+  });
 });
 
 describes.sandboxed('NativeWebAnimationRunner', {}, (env) => {
diff --git a/extensions/amp-animation/0.1/web-animation-types.js b/extensions/amp-animation/0.1/web-animation-types.js
index a495f775a538..fb5fe80c1e53 100644
--- a/extensions/amp-animation/0.1/web-animation-types.js
+++ b/extensions/amp-animation/0.1/web-animation-types.js
@@ -152,7 +152,18 @@ export let WebAnimationSubtargetDef;
 /**
  * @typedef {{
  *   scope: (!Element|undefined),
+ *   scaleByScope: (boolean|undefined),
  * }}
+ *
+ * - scope delimits selectors.
+ * - scaleByScope determines that CSS resolution should treat the scope
+ *   element as a virtual viewport, so that:
+ *   1. vw/vh units are relative to the scope's size
+ *   2. element's x() and y() coords are relative to the scope's top-left corner
+ *   3. element's size and position (width()/height()/x()/y()) are inversely
+ *      relative to the scope's transformed scale, e.g. if the scope is scaled
+ *      to 90%, the element's dimensions will be returned as if it was unscaled
+ *      to 100%.
  */
 export let WebAnimationBuilderOptionsDef;
 
diff --git a/extensions/amp-animation/0.1/web-animations.js b/extensions/amp-animation/0.1/web-animations.js
index 685283c40f0d..c2c457460bd2 100644
--- a/extensions/amp-animation/0.1/web-animations.js
+++ b/extensions/amp-animation/0.1/web-animations.js
@@ -48,6 +48,7 @@ import {getMode} from '../../../src/mode';
 import {isArray, isObject, toArray} from '../../../src/types';
 import {isExperimentOn} from '../../../src/experiments';
 import {isInFie} from '../../../src/iframe-helper';
+import {layoutRectLtwh} from '../../../src/layout-rect';
 import {map} from '../../../src/utils/object';
 import {parseCss} from './parsers/css-expr';
 
@@ -852,16 +853,20 @@ class CssContextImpl {
    * @param {!./web-animation-types.WebAnimationBuilderOptionsDef} options
    */
   constructor(win, rootNode, baseUrl, options) {
+    const {scope = null, scaleByScope = false} = options;
+
     /** @const @private */
     this.win_ = win;
 
     /** @const @private {!Document|!ShadowRoot} */
     this.rootNode_ = rootNode;
 
-    const {scope = null} = options;
     /** @const @private {?Element} */
     this.scope_ = scope;
 
+    /** @const @private {boolean} */
+    this.scaleByScope_ = scaleByScope;
+
     /** @const @private */
     this.baseUrl_ = baseUrl;
 
@@ -889,8 +894,15 @@ class CssContextImpl {
     /** @private {?string} */
     this.dim_ = null;
 
-    /** @private {?{width: number, height: number}} */
-    this.viewportSize_ = null;
+    /**
+     * @private {?{
+     *   size: {width: number, height: number},
+     *   offset: {x: number, y: number},
+     *   scaleFactorX: number,
+     *   scaleFactorY: number,
+     * }}
+     */
+    this.viewportParams_ = null;
   }
 
   /** @return {!Document|!ShadowRoot} */
@@ -1179,13 +1191,32 @@ class CssContextImpl {
 
   /** @override */
   getViewportSize() {
-    if (!this.viewportSize_) {
-      this.viewportSize_ = {
-        width: this.win_./*OK*/ innerWidth,
-        height: this.win_./*OK*/ innerHeight,
-      };
+    return this.getViewportParams_().size;
+  }
+
+  /** @private */
+  getViewportParams_() {
+    if (!this.viewportParams_) {
+      if (this.scope_ && this.scaleByScope_) {
+        const rect = this.scope_./*OK*/ getBoundingClientRect();
+        const {offsetWidth, offsetHeight} = this.scope_;
+        this.viewportParams_ = {
+          offset: {x: rect.x, y: rect.y},
+          size: {width: offsetWidth, height: offsetHeight},
+          scaleFactorX: offsetWidth / (rect.width || 1),
+          scaleFactorY: offsetHeight / (rect.height || 1),
+        };
+      } else {
+        const {innerWidth, innerHeight} = this.win_;
+        this.viewportParams_ = {
+          offset: {x: 0, y: 0},
+          size: {width: innerWidth, height: innerHeight},
+          scaleFactorX: 1,
+          scaleFactorY: 1,
+        };
+      }
     }
-    return this.viewportSize_;
+    return this.viewportParams_;
   }
 
   /** @override */
@@ -1220,13 +1251,13 @@ class CssContextImpl {
   }
 
   /** @override */
-  getCurrentElementSize() {
-    return this.getElementSize_(this.requireTarget_());
+  getCurrentElementRect() {
+    return this.getElementRect_(this.requireTarget_());
   }
 
   /** @override */
-  getElementSize(selector, selectionMethod) {
-    return this.getElementSize_(this.getElement_(selector, selectionMethod));
+  getElementRect(selector, selectionMethod) {
+    return this.getElementRect_(this.getElement_(selector, selectionMethod));
   }
 
   /**
@@ -1265,12 +1296,20 @@ class CssContextImpl {
 
   /**
    * @param {!Element} target
-   * @return {!{width: number, height: number}}
+   * @return {!../../../src/layout-rect.LayoutRectDef}
    * @private
    */
-  getElementSize_(target) {
-    const b = target./*OK*/ getBoundingClientRect();
-    return {width: b.width, height: b.height};
+  getElementRect_(target) {
+    const {offset, scaleFactorX, scaleFactorY} = this.getViewportParams_();
+    const {x, y, width, height} = target./*OK*/ getBoundingClientRect();
+
+    // This assumes default `transform-origin: center center`
+    return layoutRectLtwh(
+      (x - offset.x) * scaleFactorX,
+      (y - offset.y) * scaleFactorY,
+      width * scaleFactorX,
+      height * scaleFactorY
+    );
   }
 
   /** @override */
diff --git a/extensions/amp-animation/amp-animation.md b/extensions/amp-animation/amp-animation.md
index 6434b9492542..7df038eab8d7 100644
--- a/extensions/amp-animation/amp-animation.md
+++ b/extensions/amp-animation/amp-animation.md
@@ -398,7 +398,7 @@ CSS `@keyframes` are mostly equivalent to inlining keyframes definition in the J
 
 - For broad-platform support, vendor prefixes, e.g. `@-ms-keyframes {}` or `-moz-transform` may be needed. Vendor prefixes are not needed and not allowed in the JSON format, but in CSS they could be necessary.
 - Platforms that do not support `calc()` and `var()` will not be able to take advantage of `amp-animation` polyfills when keyframes are specified in CSS. It's thus recommended to always include fallback values in CSS.
-- CSS extensions such as [`width()`, `height()`, `num()`, `rand()`, `index()` and `length()`](#css-extensions) cannot be used in CSS.
+- CSS extensions such as [`width()`, `height()`, `x()`, `y()`, `num()`, `rand()`, `index()` and `length()`](#css-extensions) cannot be used in CSS.
 
 #### White listed properties for keyframes
 
@@ -555,7 +555,7 @@ Animation components can specify their own variables as `--var-name` fields. The
 
 ### CSS extensions
 
-`amp-animation` provides several CSS extensions for typical animations needs: `rand()`, `num()`, `width()`, and `height()`. These functions can be used everywhere where CSS values can be used within `amp-animation`, including timing and keyframes values.
+`amp-animation` provides several CSS extensions for typical animations needs: `rand()`, `num()`, `width()`, `height()`, `x()` and `y()`. These functions can be used everywhere where CSS values can be used within `amp-animation`, including timing and keyframes values.
 
 #### CSS `index()` extension
 
@@ -601,17 +601,17 @@ The second form has two arguments and returns the random value between these two
 }
 ```
 
-#### CSS `width()` and `height()` extensions
+#### CSS `width()`, `height()`, `x()` and `y()` extensions
 
-The `width()` and `height()` extensions return the width/height of the animated element or the element specified by the selector. The returned value is in pixels, e.g. `100px`.
+The `width()`/`height()` and `x()`/`y()` extensions return the size or coordinates of the animated element or the element specified by the selector. The returned value is in pixels, e.g. `100px`.
 
 The following forms are supported:
 
-- `width()` and `height()` - width/height of the animated element.
-- `width('.selector')` and `height('.selector')` - width/height of the element specified by the selector. Any CSS selector can be used. For instance, `width('#container > li')`.
-- `width(closest('.selector'))` and `height(closest('.selector'))` - width/height of the element specified by the closest selector.
+- `width()`, `height()`, `x()`, `y()` - width/height or coordinates of the animated element.
+- With a selector, like: `width('.selector')` or `x('.selector')` - dimension or coordinate of the element specified by the selector. Any CSS selector can be used. For instance, `height('#container > li')`.
+- With a closest selector, like: `height(closest('.selector'))` or `y(closest('.selector'))` - dimension or coordinate of the element specified by the closest selector.
 
-The `width()` and `height()` are epsecially useful for transforms. The `left`, `top` and similar CSS properties that can use `%` values to express animations proportional to container size. However, `transform` property interpretes `%` values differently - as a percent of the selected element. Thus, the `width()` and `height()` can be used to express transform animations in terms of container elements and similar.
+The `width()` and `height()` are especially useful for transforms. The `left`, `top` and similar CSS properties that can use `%` values to express animations proportional to container size. However, `transform` property interpretes `%` values differently - as a percent of the selected element. Thus, the `width()` and `height()` can be used to express transform animations in terms of container elements and similar.
 
 These functions can be combined with `calc()`, `var()` and other CSS expressions. For instance:
 
diff --git a/extensions/amp-base-carousel/0.1/amp-base-carousel.js b/extensions/amp-base-carousel/0.1/amp-base-carousel.js
index 7347190569aa..bd101593f143 100644
--- a/extensions/amp-base-carousel/0.1/amp-base-carousel.js
+++ b/extensions/amp-base-carousel/0.1/amp-base-carousel.js
@@ -159,6 +159,11 @@ class AmpCarousel extends AMP.BaseElement {
     return isLayoutSizeDefined(layout);
   }
 
+  /** @override */
+  prerenderAllowed() {
+    return true;
+  }
+
   /** @override */
   buildCallback() {
     this.action_ = Services.actionServiceForDoc(this.element);
diff --git a/extensions/amp-carousel/0.2/amp-carousel.js b/extensions/amp-carousel/0.2/amp-carousel.js
index a6f3ed800ec6..e829c34e3270 100644
--- a/extensions/amp-carousel/0.2/amp-carousel.js
+++ b/extensions/amp-carousel/0.2/amp-carousel.js
@@ -122,6 +122,11 @@ class AmpCarousel extends AMP.BaseElement {
     return isLayoutSizeDefined(layout);
   }
 
+  /** @override */
+  prerenderAllowed() {
+    return true;
+  }
+
   /** @override */
   buildCallback() {
     this.action_ = Services.actionServiceForDoc(this.element);
diff --git a/extensions/amp-consent/0.1/amp-consent.css b/extensions/amp-consent/0.1/amp-consent.css
index 5581a95ea8a3..48de6a9868f7 100644
--- a/extensions/amp-consent/0.1/amp-consent.css
+++ b/extensions/amp-consent/0.1/amp-consent.css
@@ -108,7 +108,7 @@ iframe.i-amphtml-consent-ui-fill {
 
 amp-consent.i-amphtml-consent-ui-iframe-active {
   width: 100% !important;
-  height: 100vh !important;
+  height: 100% !important;
   padding: 0px !important;
   margin: 0px !important;
 
diff --git a/extensions/amp-consent/0.1/cmps.js b/extensions/amp-consent/0.1/cmps.js
index 7036f24b3824..89524ad532ea 100644
--- a/extensions/amp-consent/0.1/cmps.js
+++ b/extensions/amp-consent/0.1/cmps.js
@@ -70,3 +70,9 @@ CMP_CONFIG['SourcePoint'] = {
   'checkConsentHref': 'https://sourcepoint.mgr.consensu.org/consent/v2/amp',
   'promptUISrc': 'https://amp.pm.sourcepoint.mgr.consensu.org/',
 };
+
+CMP_CONFIG['Usercentrics'] = {
+  'consentInstanceId': 'Usercentrics',
+  'checkConsentHref': 'https://consents.usercentrics.eu/amp/checkConsent',
+  'promptUISrc': 'https://amp.usercentrics.eu/amp.html',
+};
diff --git a/extensions/amp-consent/amp-consent.md b/extensions/amp-consent/amp-consent.md
index 22041e65dde6..f60b4113b526 100644
--- a/extensions/amp-consent/amp-consent.md
+++ b/extensions/amp-consent/amp-consent.md
@@ -637,5 +637,6 @@ Join in on the discussion where we are discussing [upcoming potential features](
 - Marfeel : [Website](https://www.marfeel.com/) - [Documentation](./cmps/marfeel.md)
 - Ogury : [Website](https://www.ogury.com/) - [Documentation](./cmps/ogury.md)
 - SourcePoint : [Website](https://www.sourcepoint.com/) - [Documentation](./cmps/sourcepoint.md)
+- Usercentrics : [Website](https://www.usercentrics.com/) - [Documentation](./cmps/usercentrics.md)
 
 - Your Integrated platform here!
diff --git a/extensions/amp-consent/cmps/usercentrics.md b/extensions/amp-consent/cmps/usercentrics.md
new file mode 100644
index 000000000000..7250b0922ad6
--- /dev/null
+++ b/extensions/amp-consent/cmps/usercentrics.md
@@ -0,0 +1,52 @@
+<!---
+Copyright 2020 The AMP HTML Authors. All Rights Reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+      http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS-IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+-->
+
+# Usercentrics
+
+Collect user consent with Usercentrics CMP.
+
+## Example
+
+```html
+<amp-consent id="consent" layout="nodisplay" type="Usercentrics">
+  <script type="application/json">
+    {
+      "postPromptUI": "postPromptUI",
+      "clientConfig": {
+        "id": "i3_E5TN2b"
+      }
+    }
+  </script>
+  <div id="postPromptUI">
+    Post Prompt UI
+    <button on="tap:consent.prompt(consent=Usercentrics)" role="button">
+      Manage
+    </button>
+  </div>
+</amp-consent>
+```
+
+## Configuration
+
+| Attribute |  Type  | Mandatory | Description                               |
+| --------- | :----: | :-------: | ----------------------------------------- |
+| id        | String |    yes    | Settings id, provided via Admin Interface |
+
+In order to retrieve your settings id, please use the [Usercentrics Admin Interface](https://admin.usercentrics.com/).
+
+## Support
+
+Please get in contact with [Usercentrics](https://usercentrics.com/) if you need further support.
diff --git a/extensions/amp-iframe/0.1/amp-iframe.js b/extensions/amp-iframe/0.1/amp-iframe.js
index 42ed6d805b7b..7747034d3342 100644
--- a/extensions/amp-iframe/0.1/amp-iframe.js
+++ b/extensions/amp-iframe/0.1/amp-iframe.js
@@ -14,6 +14,7 @@
  * limitations under the License.
  */
 
+import {AMPDOC_SINGLETON_NAME} from '../../../src/enums';
 import {ActionTrust} from '../../../src/action-constants';
 import {IntersectionObserverHostApi} from '../../../src/utils/intersection-observer-polyfill';
 import {LayoutPriority, isLayoutSizeDefined} from '../../../src/layout';
@@ -395,7 +396,11 @@ export class AmpIframe extends AMP.BaseElement {
     }
 
     if (this.isTrackingFrame_) {
-      if (!this.getAmpDoc().registerTrackingIframe()) {
+      if (
+        !this.getAmpDoc().registerSingleton(
+          AMPDOC_SINGLETON_NAME.TRACKING_IFRAME
+        )
+      ) {
         console /*OK*/
           .error(
             'Only 1 analytics/tracking iframe allowed per ' +
diff --git a/extensions/amp-inline-gallery/0.1/amp-inline-gallery-pagination.js b/extensions/amp-inline-gallery/0.1/amp-inline-gallery-pagination.js
index b0f25fc91b79..5062ca21df48 100644
--- a/extensions/amp-inline-gallery/0.1/amp-inline-gallery-pagination.js
+++ b/extensions/amp-inline-gallery/0.1/amp-inline-gallery-pagination.js
@@ -73,6 +73,11 @@ export class AmpInlineGalleryPagination extends AMP.BaseElement {
     return layout == Layout.FIXED_HEIGHT;
   }
 
+  /** @override */
+  prerenderAllowed() {
+    return true;
+  }
+
   /** @override */
   buildCallback() {
     this.element.appendChild(this.createDom_());
diff --git a/extensions/amp-inline-gallery/0.1/amp-inline-gallery-thumbnails.js b/extensions/amp-inline-gallery/0.1/amp-inline-gallery-thumbnails.js
index bcf7deae8285..9b47417d687e 100644
--- a/extensions/amp-inline-gallery/0.1/amp-inline-gallery-thumbnails.js
+++ b/extensions/amp-inline-gallery/0.1/amp-inline-gallery-thumbnails.js
@@ -54,6 +54,11 @@ export class AmpInlineGalleryThumbnails extends AMP.BaseElement {
     return isLayoutSizeDefined(layout);
   }
 
+  /** @override */
+  prerenderAllowed() {
+    return true;
+  }
+
   /** @override */
   buildCallback() {
     const aspectRatioWidth =
diff --git a/extensions/amp-inline-gallery/0.1/amp-inline-gallery.js b/extensions/amp-inline-gallery/0.1/amp-inline-gallery.js
index b9cd70ef5924..c359e1718e58 100644
--- a/extensions/amp-inline-gallery/0.1/amp-inline-gallery.js
+++ b/extensions/amp-inline-gallery/0.1/amp-inline-gallery.js
@@ -85,6 +85,11 @@ class AmpInlineGallery extends AMP.BaseElement {
     });
   }
 
+  /** @override */
+  prerenderAllowed() {
+    return true;
+  }
+
   /** @override */
   isLayoutSupported(layout) {
     return layout === Layout.CONTAINER;
diff --git a/extensions/amp-list/amp-list.md b/extensions/amp-list/amp-list.md
index d4867a1bea87..635f4aa07a22 100644
--- a/extensions/amp-list/amp-list.md
+++ b/extensions/amp-list/amp-list.md
@@ -220,6 +220,8 @@ In several cases, we may need the `<amp-list>` to resize on user interaction. Fo
 </amp-list>
 ```
 
+[filter formats="websites, stories"]
+
 ### Initialization from amp-state
 
 In most cases, you’ll probably want to have `<amp-list>` request JSON from a server. But `<amp-list>` can also use JSON you’ve included in an `<amp-state>`, right there in your HTML! This means rendering can occur without an additional server call, although, of course, if your page is served from an AMP cache, the data may not be fresh.
@@ -249,6 +251,8 @@ See below for a full example,
 </amp-list>
 ```
 
+[/filter]<!-- formats="websites, stories" -->
+
 ## Attributes
 
 ### src (required)
diff --git a/extensions/amp-mega-menu/0.1/amp-mega-menu.js b/extensions/amp-mega-menu/0.1/amp-mega-menu.js
index 11855c7585be..a51ceb4ca4f2 100644
--- a/extensions/amp-mega-menu/0.1/amp-mega-menu.js
+++ b/extensions/amp-mega-menu/0.1/amp-mega-menu.js
@@ -88,6 +88,11 @@ export class AmpMegaMenu extends AMP.BaseElement {
     return layout === Layout.FIXED_HEIGHT;
   }
 
+  /** @override */
+  prerenderAllowed() {
+    return true;
+  }
+
   /** @override */
   buildCallback() {
     this.action_ = Services.actionServiceForDoc(this.element);
diff --git a/extensions/amp-nested-menu/0.1/amp-nested-menu.js b/extensions/amp-nested-menu/0.1/amp-nested-menu.js
index 9521a96398b9..967b2697ddb4 100644
--- a/extensions/amp-nested-menu/0.1/amp-nested-menu.js
+++ b/extensions/amp-nested-menu/0.1/amp-nested-menu.js
@@ -120,6 +120,11 @@ export class AmpNestedMenu extends AMP.BaseElement {
     return layout == Layout.FILL;
   }
 
+  /** @override */
+  prerenderAllowed() {
+    return true;
+  }
+
   /**
    * Handler for click event on any element inside the component.
    * @param {!Event} e
diff --git a/extensions/amp-selector/0.1/amp-selector.js b/extensions/amp-selector/0.1/amp-selector.js
index 69c5a8ebd131..ac932bda6cfa 100644
--- a/extensions/amp-selector/0.1/amp-selector.js
+++ b/extensions/amp-selector/0.1/amp-selector.js
@@ -81,6 +81,11 @@ export class AmpSelector extends AMP.BaseElement {
     return true;
   }
 
+  /** @override */
+  prerenderAllowed() {
+    return true;
+  }
+
   /** @override */
   buildCallback() {
     this.action_ = Services.actionServiceForDoc(this.element);
diff --git a/extensions/amp-sidebar/0.2/amp-sidebar.js b/extensions/amp-sidebar/0.2/amp-sidebar.js
index d1a364000be0..16a4c0c96fa3 100644
--- a/extensions/amp-sidebar/0.2/amp-sidebar.js
+++ b/extensions/amp-sidebar/0.2/amp-sidebar.js
@@ -137,6 +137,11 @@ export class AmpSidebar extends AMP.BaseElement {
     );
   }
 
+  /** @override */
+  prerenderAllowed() {
+    return true;
+  }
+
   /** @override */
   buildCallback() {
     // TODO(#25022): remove this assert when cleaning up experiment post launch.
diff --git a/extensions/amp-social-share/0.1/amp-social-share.js b/extensions/amp-social-share/0.1/amp-social-share.js
index 47b08039a6ad..4e698371725a 100644
--- a/extensions/amp-social-share/0.1/amp-social-share.js
+++ b/extensions/amp-social-share/0.1/amp-social-share.js
@@ -125,6 +125,12 @@ class AmpSocialShare extends AMP.BaseElement {
 
   /** @override */
   layoutCallback() {
+    // Do not layout if the component returns before
+    // this.shareEndpoint_ is resolved from buildCallback.
+    if (!this.shareEndpoint_) {
+      return Promise.resolve();
+    }
+
     const hrefWithVars = addParamsToUrl(
       dev().assertString(this.shareEndpoint_),
       this.params_
diff --git a/extensions/amp-story-auto-ads/0.1/story-ad-localization.js b/extensions/amp-story-auto-ads/0.1/story-ad-localization.js
index b64e51ed95cb..803d34e70142 100644
--- a/extensions/amp-story-auto-ads/0.1/story-ad-localization.js
+++ b/extensions/amp-story-auto-ads/0.1/story-ad-localization.js
@@ -14,11 +14,13 @@
  * limitations under the License.
  */
 
+import {LocalizationService} from '../../../src/service/localization';
 import {
   LocalizedStringId,
   createPseudoLocale,
 } from '../../../src/localized-strings';
 import {Services} from '../../../src/services';
+import {registerServiceBuilderForDoc} from '../../../src/service';
 import LocalizedStringsAr from './_locales/ar';
 import LocalizedStringsDe from './_locales/de';
 import LocalizedStringsEn from './_locales/en';
@@ -69,6 +71,25 @@ export const CtaTypes = {
     LocalizedStringId.AMP_STORY_AUTO_ADS_BUTTON_LABEL_WATCH_EPISODE,
 };
 
+/**
+ * Util function to retrieve the localization service. Ensures we can retrieve
+ * the service synchronously without running into race conditions.
+ * @param {!Element} element
+ * @return {!../../../src/service/localization.LocalizationService}
+ */
+const getLocalizationService = (element) => {
+  let localizationService = Services.localizationForDoc(element);
+
+  if (!localizationService) {
+    localizationService = new LocalizationService(element);
+    registerServiceBuilderForDoc(element, 'localization', function () {
+      return localizationService;
+    });
+  }
+
+  return localizationService;
+};
+
 export class StoryAdLocalization {
   /**
    * @param {!Element} storyAutoAdsEl
@@ -95,9 +116,7 @@ export class StoryAdLocalization {
    * Create localization service and register all bundles.
    */
   init_() {
-    this.localizationService_ = Services.localizationForDoc(
-      this.storyAutoAdsEl_
-    );
+    this.localizationService_ = getLocalizationService(this.storyAutoAdsEl_);
 
     const enXaPseudoLocaleBundle = createPseudoLocale(
       LocalizedStringsEn,
diff --git a/extensions/amp-story-auto-ads/0.1/test/test-amp-story-auto-ads.js b/extensions/amp-story-auto-ads/0.1/test/test-amp-story-auto-ads.js
index 8eb7e0589af5..e814dca08c65 100644
--- a/extensions/amp-story-auto-ads/0.1/test/test-amp-story-auto-ads.js
+++ b/extensions/amp-story-auto-ads/0.1/test/test-amp-story-auto-ads.js
@@ -24,6 +24,7 @@ import {
 import {AmpStory} from '../../../amp-story/1.0/amp-story';
 import {AmpStoryAutoAds, Attributes} from '../amp-story-auto-ads';
 import {CommonSignals} from '../../../../src/common-signals';
+import {LocalizationService} from '../../../../src/service/localization';
 import {
   MockStoryImpl,
   addStoryAutoAdsConfig,
@@ -58,9 +59,7 @@ describes.realWin(
     beforeEach(() => {
       win = env.win;
       doc = win.document;
-      const localizationService = Services.localizationForDoc(
-        win.document.body
-      );
+      const localizationService = new LocalizationService(win.document.body);
       env.sandbox
         .stub(Services, 'localizationForDoc')
         .returns(localizationService);
diff --git a/extensions/amp-story-education/0.1/amp-story-education.js b/extensions/amp-story-education/0.1/amp-story-education.js
index 5dba48fb9668..afed051a0dd8 100644
--- a/extensions/amp-story-education/0.1/amp-story-education.js
+++ b/extensions/amp-story-education/0.1/amp-story-education.js
@@ -26,6 +26,7 @@ import {Services} from '../../../src/services';
 import {createShadowRootWithStyle} from '../../amp-story/1.0/utils';
 import {dev} from '../../../src/log';
 import {dict} from '../../../src/utils/object';
+import {getLocalizationService} from '../../amp-story/1.0/amp-story-localization-service';
 import {htmlFor} from '../../../src/static-template';
 import {removeChildren} from '../../../src/dom';
 import {toggle} from '../../../src/style';
@@ -75,7 +76,7 @@ export class AmpStoryEducation extends AMP.BaseElement {
     this.containerEl_ = this.win.document.createElement('div');
 
     /** @private @const {!../../../src/service/localization.LocalizationService} */
-    this.localizationService_ = Services.localizationForDoc(element);
+    this.localizationService_ = getLocalizationService(element);
 
     /** @private {?boolean} */
     this.storyPausedStateToRestore_ = null;
diff --git a/extensions/amp-story-education/0.1/test/test-amp-story-education.js b/extensions/amp-story-education/0.1/test/test-amp-story-education.js
index 67bf86836b5d..4cafa474d052 100644
--- a/extensions/amp-story-education/0.1/test/test-amp-story-education.js
+++ b/extensions/amp-story-education/0.1/test/test-amp-story-education.js
@@ -21,6 +21,7 @@ import {
 } from '../../../amp-story/1.0/amp-story-store-service';
 import {AmpDocSingle} from '../../../../src/service/ampdoc-impl';
 import {AmpStoryEducation, State} from '../amp-story-education';
+import {LocalizationService} from '../../../../src/service/localization';
 import {Services} from '../../../../src/services';
 import {registerServiceBuilder} from '../../../../src/service';
 
@@ -35,6 +36,11 @@ describes.realWin('amp-story-education', {amp: true}, (env) => {
   beforeEach(() => {
     win = env.win;
 
+    const localizationService = new LocalizationService(win.document.body);
+    env.sandbox
+      .stub(Services, 'localizationForDoc')
+      .returns(localizationService);
+
     storeService = new AmpStoryStoreService(win);
     registerServiceBuilder(win, 'story-store', function () {
       return storeService;
diff --git a/extensions/amp-story/0.1/amp-story-info-dialog.js b/extensions/amp-story/0.1/amp-story-info-dialog.js
index b87822d05b4f..6a5ce51e7e87 100644
--- a/extensions/amp-story/0.1/amp-story-info-dialog.js
+++ b/extensions/amp-story/0.1/amp-story-info-dialog.js
@@ -23,6 +23,7 @@ import {closest} from '../../../src/dom';
 import {createShadowRootWithStyle} from './utils';
 import {dev} from '../../../src/log';
 import {getAmpdoc} from '../../../src/service';
+import {getLocalizationService} from './amp-story-localization-service';
 import {htmlFor} from '../../../src/static-template';
 
 /** @const {string} Class to toggle the info dialog. */
@@ -55,7 +56,7 @@ export class InfoDialog {
     this.isBuilt_ = false;
 
     /** @private @const {!../../../src/service/localization.LocalizationService} */
-    this.localizationService_ = Services.localizationForDoc(parentEl);
+    this.localizationService_ = getLocalizationService(parentEl);
 
     /** @private @const {!./amp-story-store-service.AmpStoryStoreService} */
     this.storeService_ = Services.storyStoreServiceV01(this.win_);
diff --git a/extensions/amp-story/0.1/amp-story-localization-service.js b/extensions/amp-story/0.1/amp-story-localization-service.js
new file mode 100644
index 000000000000..110d3b09a836
--- /dev/null
+++ b/extensions/amp-story/0.1/amp-story-localization-service.js
@@ -0,0 +1,39 @@
+/**
+ * Copyright 2020 The AMP HTML Authors. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS-IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import {LocalizationService} from '../../../src/service/localization';
+import {Services} from '../../../src/services';
+import {registerServiceBuilderForDoc} from '../../../src/service';
+
+/**
+ * Util function to retrieve the localization service. Ensures we can retrieve
+ * the service synchronously from the amp-story codebase without running into
+ * race conditions.
+ * @param {!Element} element
+ * @return {!../../../src/service/localization.LocalizationService}
+ */
+export const getLocalizationService = (element) => {
+  let localizationService = Services.localizationForDoc(element);
+
+  if (!localizationService) {
+    localizationService = new LocalizationService(element);
+    registerServiceBuilderForDoc(element, 'localization', function () {
+      return localizationService;
+    });
+  }
+
+  return localizationService;
+};
diff --git a/extensions/amp-story/0.1/amp-story-share.js b/extensions/amp-story/0.1/amp-story-share.js
index 2f7420eb941c..1064f1e8db5e 100644
--- a/extensions/amp-story/0.1/amp-story-share.js
+++ b/extensions/amp-story/0.1/amp-story-share.js
@@ -22,6 +22,7 @@ import {
 } from '../../../src/clipboard';
 import {dev, devAssert, user} from '../../../src/log';
 import {dict, map} from './../../../src/utils/object';
+import {getLocalizationService} from './amp-story-localization-service';
 import {isObject} from '../../../src/types';
 import {listen} from '../../../src/event-helper';
 import {px, setImportantStyles} from '../../../src/style';
@@ -268,7 +269,7 @@ export class ShareWidget {
     const url = Services.documentInfoForDoc(this.getAmpDoc_()).canonicalUrl;
 
     if (!copyTextToClipboard(this.win, url)) {
-      const localizationService = Services.localizationForDoc(this.parentEl_);
+      const localizationService = getLocalizationService(this.parentEl_);
       devAssert(localizationService, 'Could not retrieve LocalizationService.');
       const failureString = localizationService.getLocalizedString(
         LocalizedStringId.AMP_STORY_SHARING_CLIPBOARD_FAILURE_TEXT
diff --git a/extensions/amp-story/0.1/amp-story.js b/extensions/amp-story/0.1/amp-story.js
index c2aa9775bebd..bb782e7321fe 100644
--- a/extensions/amp-story/0.1/amp-story.js
+++ b/extensions/amp-story/0.1/amp-story.js
@@ -92,6 +92,7 @@ import {dict} from '../../../src/utils/object';
 import {escapeCssSelectorIdent} from '../../../src/css';
 import {findIndex} from '../../../src/utils/array';
 import {getDetail} from '../../../src/event-helper';
+import {getLocalizationService} from './amp-story-localization-service';
 import {getMode} from '../../../src/mode';
 import {getSourceOrigin, parseUrlDeprecated} from '../../../src/url';
 import {getState} from '../../../src/history';
@@ -211,7 +212,7 @@ export class AmpStory extends AMP.BaseElement {
     this.vsync_ = this.getVsync();
 
     /** @private @const {!../../../src/service/localization.LocalizationService} */
-    this.localizationService_ = Services.localizationForDoc(this.element);
+    this.localizationService_ = getLocalizationService(this.element);
 
     this.localizationService_
       .registerLocalizedStringBundle('default', LocalizedStringsDefault)
diff --git a/extensions/amp-story/0.1/simple-template.js b/extensions/amp-story/0.1/simple-template.js
index 867258756acb..b2aaa585c673 100644
--- a/extensions/amp-story/0.1/simple-template.js
+++ b/extensions/amp-story/0.1/simple-template.js
@@ -14,9 +14,10 @@
  * limitations under the License.
  */
 import {LocalizedStringId} from '../../../src/localized-strings'; // eslint-disable-line no-unused-vars
-import {Services} from '../../../src/services';
+
 import {createElementWithAttributes} from '../../../src/dom';
 import {devAssert} from '../../../src/log';
+import {getLocalizationService} from './amp-story-localization-service';
 import {isArray} from '../../../src/types';
 
 /**
@@ -75,9 +76,7 @@ function renderSingle(doc, elementDef) {
     : doc.createElement(elementDef.tag);
 
   if (elementDef.localizedStringId) {
-    const localizationService = Services.localizationForDoc(
-      devAssert(doc.body)
-    );
+    const localizationService = getLocalizationService(devAssert(doc.body));
 
     devAssert(localizationService, 'Could not retrieve LocalizationService.');
     el.textContent = localizationService.getLocalizedString(
diff --git a/extensions/amp-story/0.1/test/test-amp-story-info-dialog.js b/extensions/amp-story/0.1/test/test-amp-story-info-dialog.js
index 9dee0ef57e9c..cc645be6bf20 100644
--- a/extensions/amp-story/0.1/test/test-amp-story-info-dialog.js
+++ b/extensions/amp-story/0.1/test/test-amp-story-info-dialog.js
@@ -24,10 +24,11 @@ import {
   InfoDialog,
   MOREINFO_VISIBLE_CLASS,
 } from '../amp-story-info-dialog';
+import {LocalizationService} from '../../../../src/service/localization';
 import {Services} from '../../../../src/services';
 import {registerServiceBuilder} from '../../../../src/service';
 
-describes.realWin('amp-story-share-menu', {amp: true}, (env) => {
+describes.realWin('amp-story-info-dialog', {amp: true}, (env) => {
   let moreInfoLinkUrl;
   let embedded;
   let parentEl;
@@ -39,6 +40,10 @@ describes.realWin('amp-story-share-menu', {amp: true}, (env) => {
 
   beforeEach(() => {
     win = env.win;
+    const localizationService = new LocalizationService(win.document.body);
+    env.sandbox
+      .stub(Services, 'localizationForDoc')
+      .returns(localizationService);
     storeService = new AmpStoryStoreService(win);
     embedded = true;
     registerServiceBuilder(win, 'story-store', function () {
diff --git a/extensions/amp-story/0.1/test/test-amp-story.js b/extensions/amp-story/0.1/test/test-amp-story.js
index b8d87c18541d..58ea1da0f0de 100644
--- a/extensions/amp-story/0.1/test/test-amp-story.js
+++ b/extensions/amp-story/0.1/test/test-amp-story.js
@@ -13,11 +13,13 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+
 import {Action} from '../amp-story-store-service';
 import {AmpStory} from '../amp-story';
 import {AmpStoryPage} from '../amp-story-page';
 import {EventType} from '../events';
 import {Keys} from '../../../../src/utils/key-codes';
+import {LocalizationService} from '../../../../src/service/localization';
 import {PaginationButtons} from '../pagination-buttons';
 import {Services} from '../../../../src/services';
 
@@ -88,9 +90,7 @@ describes.realWin(
 
     beforeEach(() => {
       win = env.win;
-      const localizationService = Services.localizationForDoc(
-        win.document.body
-      );
+      const localizationService = new LocalizationService(win.document.body);
       env.sandbox
         .stub(Services, 'localizationForDoc')
         .returns(localizationService);
diff --git a/extensions/amp-story/1.0/_locales/default.js b/extensions/amp-story/1.0/_locales/default.js
index baaaf96d1ff3..1ac81815e39e 100644
--- a/extensions/amp-story/1.0/_locales/default.js
+++ b/extensions/amp-story/1.0/_locales/default.js
@@ -80,6 +80,18 @@ const strings = {
   [LocalizedStringId.AMP_STORY_HAS_NEW_PAGE_TEXT]: {
     string: 'Updated',
   },
+  [LocalizedStringId.AMP_STORY_QUIZ_ANSWER_CHOICE_A]: {
+    string: 'A',
+  },
+  [LocalizedStringId.AMP_STORY_QUIZ_ANSWER_CHOICE_B]: {
+    string: 'B',
+  },
+  [LocalizedStringId.AMP_STORY_QUIZ_ANSWER_CHOICE_C]: {
+    string: 'C',
+  },
+  [LocalizedStringId.AMP_STORY_QUIZ_ANSWER_CHOICE_D]: {
+    string: 'D',
+  },
   [LocalizedStringId.AMP_STORY_SHARING_CLIPBOARD_FAILURE_TEXT]: {
     string: ':(',
   },
diff --git a/extensions/amp-story/1.0/amp-story-embedded-component.js b/extensions/amp-story/1.0/amp-story-embedded-component.js
index 3b31eac60719..bfb280c8f801 100644
--- a/extensions/amp-story/1.0/amp-story-embedded-component.js
+++ b/extensions/amp-story/1.0/amp-story-embedded-component.js
@@ -37,6 +37,7 @@ import {createShadowRootWithStyle, getSourceOriginForElement} from './utils';
 import {dev, devAssert, user, userAssert} from '../../../src/log';
 import {dict} from '../../../src/utils/object';
 import {getAmpdoc} from '../../../src/service';
+import {getLocalizationService} from './amp-story-localization-service';
 import {htmlFor, htmlRefs} from '../../../src/static-template';
 import {isProtocolValid, parseUrlDeprecated} from '../../../src/url';
 import {px, resetStyles, setImportantStyles, toggle} from '../../../src/style';
@@ -1095,7 +1096,7 @@ export class AmpStoryEmbeddedComponent {
   updateTooltipText_(target, embedConfig) {
     const tooltipText =
       target.getAttribute('data-tooltip-text') ||
-      Services.localizationForDoc(this.storyEl_).getLocalizedString(
+      getLocalizationService(this.storyEl_).getLocalizedString(
         embedConfig.localizedStringId
       ) ||
       getSourceOriginForElement(target, this.getElementHref_(target));
diff --git a/extensions/amp-story/1.0/amp-story-info-dialog.js b/extensions/amp-story/1.0/amp-story-info-dialog.js
index e82983f775a2..5dcb05100180 100644
--- a/extensions/amp-story/1.0/amp-story-info-dialog.js
+++ b/extensions/amp-story/1.0/amp-story-info-dialog.js
@@ -32,6 +32,7 @@ import {closest} from '../../../src/dom';
 import {createShadowRootWithStyle} from './utils';
 import {dev} from '../../../src/log';
 import {getAmpdoc} from '../../../src/service';
+import {getLocalizationService} from './amp-story-localization-service';
 import {htmlFor} from '../../../src/static-template';
 
 /** @const {string} Class to toggle the info dialog. */
@@ -64,7 +65,7 @@ export class InfoDialog {
     this.isBuilt_ = false;
 
     /** @private @const {!../../../src/service/localization.LocalizationService} */
-    this.localizationService_ = Services.localizationForDoc(parentEl);
+    this.localizationService_ = getLocalizationService(parentEl);
 
     /** @private @const {!./amp-story-store-service.AmpStoryStoreService} */
     this.storeService_ = getStoreService(this.win_);
diff --git a/extensions/amp-story/1.0/amp-story-localization-service.js b/extensions/amp-story/1.0/amp-story-localization-service.js
new file mode 100644
index 000000000000..110d3b09a836
--- /dev/null
+++ b/extensions/amp-story/1.0/amp-story-localization-service.js
@@ -0,0 +1,39 @@
+/**
+ * Copyright 2020 The AMP HTML Authors. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS-IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import {LocalizationService} from '../../../src/service/localization';
+import {Services} from '../../../src/services';
+import {registerServiceBuilderForDoc} from '../../../src/service';
+
+/**
+ * Util function to retrieve the localization service. Ensures we can retrieve
+ * the service synchronously from the amp-story codebase without running into
+ * race conditions.
+ * @param {!Element} element
+ * @return {!../../../src/service/localization.LocalizationService}
+ */
+export const getLocalizationService = (element) => {
+  let localizationService = Services.localizationForDoc(element);
+
+  if (!localizationService) {
+    localizationService = new LocalizationService(element);
+    registerServiceBuilderForDoc(element, 'localization', function () {
+      return localizationService;
+    });
+  }
+
+  return localizationService;
+};
diff --git a/extensions/amp-story/1.0/amp-story-page.js b/extensions/amp-story/1.0/amp-story-page.js
index a90d3182dc67..5a726126a67b 100644
--- a/extensions/amp-story/1.0/amp-story-page.js
+++ b/extensions/amp-story/1.0/amp-story-page.js
@@ -69,6 +69,7 @@ import {dict} from '../../../src/utils/object';
 import {getAmpdoc} from '../../../src/service';
 import {getData, listen} from '../../../src/event-helper';
 import {getFriendlyIframeEmbedOptional} from '../../../src/iframe-helper';
+import {getLocalizationService} from './amp-story-localization-service';
 import {getLogEntries} from './logging';
 import {getMediaPerformanceMetricsService} from './media-performance-metrics-service';
 import {getMode} from '../../../src/mode';
@@ -1529,7 +1530,10 @@ export class AmpStoryPage extends AMP.BaseElement {
     const videoEls = this.getAllVideos_();
 
     if (videoEls.length) {
-      this.debounceToggleLoadingSpinner_(true);
+      const alreadyPlaying = videoEls.some((video) => video.currentTime != 0);
+      if (!alreadyPlaying) {
+        this.debounceToggleLoadingSpinner_(true);
+      }
     }
 
     Array.prototype.forEach.call(videoEls, (videoEl) => {
@@ -1642,7 +1646,7 @@ export class AmpStoryPage extends AMP.BaseElement {
     const labelEl = this.playMessageEl_.querySelector(
       '.i-amphtml-story-page-play-label'
     );
-    labelEl.textContent = Services.localizationForDoc(
+    labelEl.textContent = getLocalizationService(
       this.element
     ).getLocalizedString(LocalizedStringId.AMP_STORY_PAGE_PLAY_VIDEO);
 
@@ -1689,7 +1693,7 @@ export class AmpStoryPage extends AMP.BaseElement {
     const labelEl = this.errorMessageEl_.querySelector(
       '.i-amphtml-story-page-error-label'
     );
-    labelEl.textContent = Services.localizationForDoc(
+    labelEl.textContent = getLocalizationService(
       this.element
     ).getLocalizedString(LocalizedStringId.AMP_STORY_PAGE_ERROR_VIDEO);
 
@@ -1744,7 +1748,7 @@ export class AmpStoryPage extends AMP.BaseElement {
       const openLabelAttr = attachmentEl.getAttribute('data-cta-text');
       const openLabel =
         (openLabelAttr && openLabelAttr.trim()) ||
-        Services.localizationForDoc(this.element).getLocalizedString(
+        getLocalizationService(this.element).getLocalizedString(
           LocalizedStringId.AMP_STORY_PAGE_ATTACHMENT_OPEN_LABEL
         );
 
diff --git a/extensions/amp-story/1.0/amp-story-reaction-quiz.css b/extensions/amp-story/1.0/amp-story-reaction-quiz.css
index 2f140af75ba5..a0c1014158a0 100644
--- a/extensions/amp-story/1.0/amp-story-reaction-quiz.css
+++ b/extensions/amp-story/1.0/amp-story-reaction-quiz.css
@@ -267,11 +267,11 @@
      left: 101% !important;
  }
  
- .i-amphtml-story-reaction-post-selection.i-amphtml-story-reaction-has-data .i-amphtml-story-reaction-option-selected[correct].i-amphtml-story-reaction-quiz-option {
+ .i-amphtml-story-reaction-post-selection .i-amphtml-story-reaction-option-selected[correct].i-amphtml-story-reaction-quiz-option {
      background: var(--correct-color) !important;
  }
  
- .i-amphtml-story-reaction-post-selection.i-amphtml-story-reaction-has-data .i-amphtml-story-reaction-option-selected:not([correct]).i-amphtml-story-reaction-quiz-option {
+ .i-amphtml-story-reaction-post-selection .i-amphtml-story-reaction-option-selected:not([correct]).i-amphtml-story-reaction-quiz-option {
      background: var(--incorrect-color) !important;
  }
  
diff --git a/extensions/amp-story/1.0/amp-story-reaction-quiz.js b/extensions/amp-story/1.0/amp-story-reaction-quiz.js
index a35fee6a3d05..bdaf70113ed6 100644
--- a/extensions/amp-story/1.0/amp-story-reaction-quiz.js
+++ b/extensions/amp-story/1.0/amp-story-reaction-quiz.js
@@ -17,15 +17,12 @@
 import {AmpStoryReaction, ReactionType} from './amp-story-reaction';
 import {CSS} from '../../../build/amp-story-reaction-quiz-1.0.css';
 import {LocalizedStringId} from '../../../src/localized-strings';
-import {Services} from '../../../src/services';
 import {createShadowRootWithStyle} from './utils';
-import {dev} from '../../../src/log';
+import {dev, devAssert} from '../../../src/log';
+import {getLocalizationService} from './amp-story-localization-service';
 import {htmlFor} from '../../../src/static-template';
 import {toArray} from '../../../src/types';
 
-/** @const {string} */
-const TAG = 'amp-story-reaction-quiz';
-
 /**
  * Generates the template for the quiz.
  *
@@ -72,19 +69,24 @@ export class AmpStoryReactionQuiz extends AmpStoryReaction {
     this.answerChoiceOptions_ = ['A', 'B', 'C', 'D'];
 
     /** @private {!../../../src/service/localization.LocalizationService} */
-    this.localizationService_ = Services.localizationForDoc(element);
+    this.localizationService_ = getLocalizationService(element);
   }
 
   /** @override */
   buildCallback() {
     super.buildCallback();
-    createShadowRootWithStyle(this.element, this.rootEl_, CSS);
+    createShadowRootWithStyle(
+      this.element,
+      dev().assertElement(this.rootEl_),
+      CSS
+    );
   }
 
   /** @override */
   buildComponent(element) {
     this.rootEl_ = buildQuizTemplate(element);
     this.attachContent_(this.rootEl_);
+    return this.rootEl_;
   }
 
   /**
@@ -103,8 +105,8 @@ export class AmpStoryReactionQuiz extends AmpStoryReaction {
 
     // First child must be heading h1-h3
     if (!['h1', 'h2', 'h3'].includes(promptInput.tagName.toLowerCase())) {
-      dev().error(
-        TAG,
+      devAssert(
+        false,
         'The first child must be a heading element <h1>, <h2>, or <h3>'
       );
       this.rootEl_.removeChild(promptContainer);
@@ -119,9 +121,10 @@ export class AmpStoryReactionQuiz extends AmpStoryReaction {
     }
 
     const options = toArray(this.element.querySelectorAll('option'));
-    if (options.length < 2 || options.length > 4) {
-      dev().error(TAG, 'Improper number of options');
-    }
+    devAssert(
+      options.length >= 2 && options.length <= 4,
+      'Improper number of options'
+    );
 
     // Localize the answer choice options
     this.answerChoiceOptions_ = this.answerChoiceOptions_.map((choice) => {
@@ -131,9 +134,7 @@ export class AmpStoryReactionQuiz extends AmpStoryReaction {
     });
     options.forEach((option, index) => this.configureOption_(option, index));
 
-    if (this.element.children.length !== 0) {
-      dev().error(TAG, 'Too many children');
-    }
+    devAssert(this.element.children.length == 0, 'Too many children');
   }
 
   /**
@@ -188,23 +189,21 @@ export class AmpStoryReactionQuiz extends AmpStoryReaction {
   /**
    * @override
    */
-  updateOptionPercentages_(responseData) {
-    if (!responseData) {
+  updateOptionPercentages_(optionsData) {
+    if (!optionsData) {
       return;
     }
 
-    const options = toArray(
-      this.rootEl_.querySelectorAll('.i-amphtml-story-reaction-option')
-    );
+    const optionElements = this.getOptionElements();
 
-    const percentages = this.preprocessPercentages_(responseData);
+    const percentages = this.preprocessPercentages_(optionsData);
 
-    toArray(responseData['responses']).forEach((response) => {
+    optionsData.forEach((optionData, index) => {
       // TODO(jackbsteinberg): Add i18n support for various ways of displaying percentages.
-      if (options[response['reactionValue']]) {
-        options[response['reactionValue']].querySelector(
+      if (optionElements[index]) {
+        optionElements[index].querySelector(
           '.i-amphtml-story-reaction-quiz-percentage-text'
-        ).textContent = `${percentages[response['reactionValue']]}%`;
+        ).textContent = `${percentages[index]}%`;
       }
     });
 
diff --git a/extensions/amp-story/1.0/amp-story-reaction.js b/extensions/amp-story/1.0/amp-story-reaction.js
index 33fe6c5d8b67..219daad79738 100644
--- a/extensions/amp-story/1.0/amp-story-reaction.js
+++ b/extensions/amp-story/1.0/amp-story-reaction.js
@@ -23,12 +23,17 @@ import {AnalyticsVariable, getVariableService} from './variable-service';
 import {CSS} from '../../../build/amp-story-reaction-1.0.css';
 import {Services} from '../../../src/services';
 import {StateProperty, getStoreService} from './amp-story-store-service';
-import {addParamsToUrl, assertAbsoluteHttpOrHttpsUrl} from '../../../src/url';
+import {
+  addParamsToUrl,
+  appendPathToUrl,
+  assertAbsoluteHttpOrHttpsUrl,
+} from '../../../src/url';
 import {closest} from '../../../src/dom';
 import {createShadowRootWithStyle} from './utils';
-import {dev} from '../../../src/log';
+import {dev, devAssert} from '../../../src/log';
 import {dict} from '../../../src/utils/object';
 import {getRequestService} from './amp-story-request-service';
+import {toArray} from '../../../src/types';
 
 /** @const {string} */
 const TAG = 'amp-story-reaction';
@@ -47,7 +52,7 @@ const ENDPOINT_INVALID_ERROR =
 
 /**
  * @typedef {{
- *    reactionValue: number,
+ *    optionIndex: number,
  *    totalCount: number,
  *    selectedByUser: boolean,
  * }}
@@ -56,9 +61,7 @@ export let ReactionOptionType;
 
 /**
  * @typedef {{
- *    totalResponseCount: number,
- *    hasUserResponded: boolean,
- *    responses: !Array<ReactionOptionType>,
+ *    options: !Array<ReactionOptionType>,
  * }}
  */
 export let ReactionResponseType;
@@ -107,8 +110,8 @@ export class AmpStoryReaction extends AMP.BaseElement {
     /** @protected {boolean} */
     this.hasUserSelection_ = false;
 
-    /** @protected {!Element} */
-    this.rootEl_;
+    /** @protected {?Element} */
+    this.rootEl_ = null;
 
     /** @protected {?string} */
     this.reactionId_ = null;
@@ -117,30 +120,64 @@ export class AmpStoryReaction extends AMP.BaseElement {
     this.requestService_ = getRequestService(this.win, this.element);
 
     /** @protected {?Promise<?ReactionResponseType|?JsonObject|undefined>} */
-    this.responseDataPromise_ = null;
+    this.backendDataPromise_ = null;
+
+    /** @protected {?Array<!ReactionOptionType>} */
+    this.optionsData_ = null;
 
-    /** @protected {?ReactionResponseType} */
-    this.responseData_ = null;
+    /** @protected {?Array<!Element>} */
+    this.optionElements_ = null;
 
     /** @const @protected {!./amp-story-store-service.AmpStoryStoreService} */
     this.storeService_ = getStoreService(this.win);
 
+    /** @protected {../../../src/service/url-impl.Url} */
+    this.urlService_ = Services.urlForDoc(this.element);
+
     /** @const @protected {!./variable-service.AmpStoryVariableService} */
     this.variableService_ = getVariableService(this.win);
   }
 
+  /**
+   * Gets the root element.
+   * @visibleForTesting
+   * @return {?Element}
+   */
+  getRootElement() {
+    return this.rootEl_;
+  }
+
+  /**
+   * Gets the options.
+   * @protected
+   * @return {!Array<!Element>}
+   */
+  getOptionElements() {
+    if (!this.optionElements_) {
+      this.optionElements_ = toArray(
+        this.rootEl_.querySelectorAll('.i-amphtml-story-reaction-option')
+      );
+    }
+    return this.optionElements_;
+  }
+
   /** @override */
   buildCallback() {
-    this.buildComponent(this.element);
+    this.rootEl_ = this.buildComponent(this.element);
     this.element.classList.add('i-amphtml-story-reaction');
     this.adjustGridLayer_();
     this.initializeListeners_();
-    createShadowRootWithStyle(this.element, this.rootEl_, CSS);
+    createShadowRootWithStyle(
+      this.element,
+      dev().assertElement(this.rootEl_),
+      CSS
+    );
   }
 
   /**
    * Generates the template in rootEl_ and fills up with options.
    * @param {!Element} unusedElement
+   * @return {!Element} rootEl_
    * @protected @abstract
    */
   buildComponent(unusedElement) {
@@ -149,7 +186,7 @@ export class AmpStoryReaction extends AMP.BaseElement {
 
   /** @override */
   layoutCallback() {
-    return (this.responseDataPromise_ = this.element.hasAttribute('endpoint')
+    return (this.backendDataPromise_ = this.element.hasAttribute('endpoint')
       ? this.retrieveReactionData_()
       : Promise.resolve());
   }
@@ -284,36 +321,30 @@ export class AmpStoryReaction extends AMP.BaseElement {
    * Called when user has responded (in this session or before).
    *
    * @protected @abstract
-   * @param {!ReactionResponseType} unusedResponseData
+   * @param {!Array<!ReactionOptionType>} unusedOptionsData
    */
-  updateOptionPercentages_(unusedResponseData) {
+  updateOptionPercentages_(unusedOptionsData) {
     // Subclass must implement
   }
 
   /**
    * Preprocess the percentages for display.
    *
-   * @param {ReactionResponseType} responseData
+   * @param {!Array<!ReactionOptionType>} optionsData
    * @return {Array<number>}
    * @protected
    */
-  preprocessPercentages_(responseData) {
-    let percentages = [];
-
-    for (let i = 0; i < responseData['responses'].length; i++) {
-      percentages[i] = (
-        100 *
-        (responseData['responses'][i]['totalCount'] /
-          responseData['totalResponseCount'])
-      ).toFixed(2);
-    }
-
-    let total = percentages.reduce(
-      (currentTotal, currentValue) =>
-        (currentTotal += Math.round(currentValue)),
+  preprocessPercentages_(optionsData) {
+    const totalResponseCount = optionsData.reduce(
+      (acc, response) => acc + response['totalCount'],
       0
     );
 
+    let percentages = optionsData.map((e) =>
+      ((100 * e['totalCount']) / totalResponseCount).toFixed(2)
+    );
+    let total = percentages.reduce((acc, x) => acc + Math.round(x), 0);
+
     // Special case: divide remainders by three if they break 100,
     // 3 is the maximum above 100 the remainders can add.
     if (total > 100) {
@@ -322,12 +353,7 @@ export class AmpStoryReaction extends AMP.BaseElement {
           2
         )
       );
-
-      total = percentages.reduce(
-        (currentTotal, currentValue) =>
-          (currentTotal += Math.round(currentValue)),
-        0
-      );
+      total = percentages.reduce((acc, x) => (acc += Math.round(x)), 0);
     }
 
     if (total === 100) {
@@ -380,9 +406,7 @@ export class AmpStoryReaction extends AMP.BaseElement {
       );
     });
 
-    percentages = finalPercentages;
-
-    return percentages;
+    return finalPercentages;
   }
 
   /**
@@ -392,7 +416,7 @@ export class AmpStoryReaction extends AMP.BaseElement {
    * @private
    */
   handleOptionSelection_(optionEl) {
-    this.responseDataPromise_.then(() => {
+    this.backendDataPromise_.then(() => {
       if (this.hasUserSelection_) {
         return;
       }
@@ -400,26 +424,20 @@ export class AmpStoryReaction extends AMP.BaseElement {
       this.triggerAnalytics_(optionEl);
       this.hasUserSelection_ = true;
 
-      if (this.responseData_) {
-        this.responseData_['totalResponseCount']++;
-        /** @type {!Array} */ (this.responseData_['responses']).forEach(
-          (response) => {
-            if (Number(response['reactionValue']) === optionEl.optionIndex_) {
-              response['totalCount']++;
-            }
-          }
-        );
+      if (this.optionsData_) {
+        this.optionsData_[optionEl.optionIndex_]['totalCount']++;
+        this.optionsData_[optionEl.optionIndex_]['selectedByUser'] = true;
       }
 
       this.mutateElement(() => {
-        if (this.responseData_) {
-          this.updateOptionPercentages_(this.responseData_);
+        if (this.optionsData_) {
+          this.updateOptionPercentages_(this.optionsData_);
         }
         this.updateToPostSelectionState_(optionEl);
       });
 
       if (this.element.hasAttribute('endpoint')) {
-        this.updateReactionData_(optionEl.optionIndex_);
+        this.executeReactionRequest_('POST', optionEl.optionIndex_);
       }
     });
   }
@@ -431,72 +449,53 @@ export class AmpStoryReaction extends AMP.BaseElement {
    * @private
    */
   retrieveReactionData_() {
-    return this.executeReactionRequest_(
-      dict({
-        'method': 'GET',
-      })
-    )
-      .then((response) => {
-        this.handleSuccessfulDataRetrieval_(response);
-      })
-      .catch((error) => {
-        dev().error(TAG, error);
-      });
-  }
-
-  /**
-   * Update the Reaction data in the datastore
-   *
-   * @param {number} reactionValue
-   * @private
-   */
-  updateReactionData_(reactionValue) {
-    this.executeReactionRequest_(
-      dict({
-        'method': 'POST',
-      }),
-      reactionValue
-    ).catch((error) => {
-      dev().error(TAG, error);
+    return this.executeReactionRequest_('GET').then((response) => {
+      this.handleSuccessfulDataRetrieval_(
+        /** @type {ReactionResponseType} */ (response)
+      );
     });
   }
 
   /**
    * Executes a Reactions API call.
    *
-   * @param {Object} requestOptions
-   * @param {number=} reactionValue
-   * @return {Promise<ReactionResponseType|undefined>}
+   * @param {string} method GET or POST.
+   * @param {number=} optionSelected
+   * @return {!Promise<!ReactionResponseType|string>}
    * @private
    */
-  executeReactionRequest_(requestOptions, reactionValue) {
-    if (!assertAbsoluteHttpOrHttpsUrl(this.element.getAttribute('endpoint'))) {
+  executeReactionRequest_(method, optionSelected = undefined) {
+    let url = this.element.getAttribute('endpoint');
+    if (!assertAbsoluteHttpOrHttpsUrl(url)) {
       return Promise.reject(ENDPOINT_INVALID_ERROR);
     }
 
-    if (this.reactionId_ === null) {
+    if (!this.reactionId_) {
       const pageId = closest(dev().assertElement(this.element), (el) => {
         return el.tagName.toLowerCase() === 'amp-story-page';
       }).getAttribute('id');
-
-      this.reactionId_ = `CANONICAL_URL#page=${pageId}`;
+      this.reactionId_ = `CANONICAL_URL+${pageId}`;
     }
 
-    const requestVars = dict({
-      'reactionType': this.reactionType_,
-      'reactionId': this.reactionId_,
-    });
-
-    let url = this.element.getAttribute('endpoint');
-
     return this.getClientId_().then((clientId) => {
-      requestVars['clientId'] = clientId;
+      const requestOptions = {'method': method};
+      const requestParams = dict({
+        'reactionType': this.reactionType_,
+        'clientId': clientId,
+      });
+      url = appendPathToUrl(
+        this.urlService_.parse(url),
+        dev().assertString(this.reactionId_)
+      );
       if (requestOptions['method'] === 'POST') {
-        requestVars['reactionValue'] = reactionValue;
-        requestOptions['body'] = requestVars;
+        requestOptions['body'] = {'optionSelected': optionSelected};
+        requestOptions['headers'] = {'Content-Type': 'application/json'};
+        url = appendPathToUrl(this.urlService_.parse(url), '/react');
       }
-      url = addParamsToUrl(url, requestVars);
-      return this.requestService_.executeRequest(url, requestOptions);
+      url = addParamsToUrl(url, requestParams);
+      return this.requestService_
+        .executeRequest(url, requestOptions)
+        .catch((err) => dev().error(TAG, err));
     });
   }
 
@@ -505,11 +504,9 @@ export class AmpStoryReaction extends AMP.BaseElement {
    *
    * RESPONSE FORMAT
    * {
-   *  totalResponseCount: <number>
-   *  hasUserResponded: <boolean>
-   *  responses: [
+   *  options: [
    *    {
-   *      reactionValue:
+   *      optionIndex:
    *      totalCount:
    *      selectedByUser:
    *    },
@@ -520,47 +517,45 @@ export class AmpStoryReaction extends AMP.BaseElement {
    * @private
    */
   handleSuccessfulDataRetrieval_(response) {
-    if (!(response && 'data' in response)) {
+    if (!(response && response['options'])) {
+      devAssert(
+        response && 'options' in response,
+        `Invalid reaction response, expected { data: ReactionResponseType, ...} but received ${response}`
+      );
       dev().error(
         TAG,
         `Invalid reaction response, expected { data: ReactionResponseType, ...} but received ${response}`
       );
       return;
     }
-
-    this.responseData_ = response.data;
-
-    this.hasUserSelection_ = this.responseData_.hasUserResponded;
-    if (this.hasUserSelection_) {
-      this.updateReactionOnDataRetrieval_(response.data);
-    }
+    const numOptions = this.rootEl_.querySelectorAll(
+      '.i-amphtml-story-reaction-option'
+    ).length;
+    // Only keep the visible options to ensure visible percentages add up to 100.
+    this.updateReactionOnDataRetrieval_(
+      response['options'].slice(0, numOptions)
+    );
   }
 
   /**
    * Updates the quiz to reflect the state of the remote data.
-   * @param {!ReactionResponseType} data
+   * @param {!Array<ReactionOptionType>} data
    * @private
    */
   updateReactionOnDataRetrieval_(data) {
-    let selectedOptionKey;
-    /** @type {!Array} */ (data['responses']).forEach((response) => {
-      if (response.selectedByUser) {
-        selectedOptionKey = response.reactionValue;
-      }
-    });
-
-    if (selectedOptionKey === undefined) {
-      dev().error(TAG, `The user-selected reaction could not be found`);
-      return;
-    }
-
     const options = this.rootEl_.querySelectorAll(
       '.i-amphtml-story-reaction-option'
     );
 
-    this.mutateElement(() => {
-      this.updateOptionPercentages_(data);
-      this.updateToPostSelectionState_(options[selectedOptionKey]);
+    this.optionsData_ = data;
+    data.forEach((response, index) => {
+      if (response.selectedByUser) {
+        this.hasUserSelection_ = true;
+        this.mutateElement(() => {
+          this.updateOptionPercentages_(data);
+          this.updateToPostSelectionState_(options[index]);
+        });
+      }
     });
   }
 
@@ -573,7 +568,7 @@ export class AmpStoryReaction extends AMP.BaseElement {
     this.rootEl_.classList.add('i-amphtml-story-reaction-post-selection');
     selectedOption.classList.add('i-amphtml-story-reaction-option-selected');
 
-    if (this.responseData_) {
+    if (this.optionsData_) {
       this.rootEl_.classList.add('i-amphtml-story-reaction-has-data');
     }
   }
diff --git a/extensions/amp-story/1.0/amp-story-share.js b/extensions/amp-story/1.0/amp-story-share.js
index 62168705a473..c7facd45e235 100644
--- a/extensions/amp-story/1.0/amp-story-share.js
+++ b/extensions/amp-story/1.0/amp-story-share.js
@@ -22,6 +22,7 @@ import {
 } from '../../../src/clipboard';
 import {dev, devAssert, user} from '../../../src/log';
 import {dict, map} from './../../../src/utils/object';
+import {getLocalizationService} from './amp-story-localization-service';
 import {getRequestService} from './amp-story-request-service';
 import {isObject} from '../../../src/types';
 import {listen} from '../../../src/event-helper';
@@ -285,7 +286,7 @@ export class ShareWidget {
     const url = Services.documentInfoForDoc(this.getAmpDoc_()).canonicalUrl;
 
     if (!copyTextToClipboard(this.win, url)) {
-      const localizationService = Services.localizationForDoc(this.storyEl);
+      const localizationService = getLocalizationService(this.storyEl);
       devAssert(localizationService, 'Could not retrieve LocalizationService.');
       const failureString = localizationService.getLocalizedString(
         LocalizedStringId.AMP_STORY_SHARING_CLIPBOARD_FAILURE_TEXT
diff --git a/extensions/amp-story/1.0/amp-story-viewport-warning-layer.js b/extensions/amp-story/1.0/amp-story-viewport-warning-layer.js
index f7601ce19815..3ef430f3a573 100644
--- a/extensions/amp-story/1.0/amp-story-viewport-warning-layer.js
+++ b/extensions/amp-story/1.0/amp-story-viewport-warning-layer.js
@@ -23,6 +23,7 @@ import {
   getStoreService,
 } from './amp-story-store-service';
 import {createShadowRootWithStyle} from './utils';
+import {getLocalizationService} from './amp-story-localization-service';
 import {htmlFor} from '../../../src/static-template';
 import {listen} from '../../../src/event-helper';
 import {throttle} from '../../../src/utils/rate-limit';
@@ -114,7 +115,7 @@ export class ViewportWarningLayer {
     }
 
     this.overlayEl_ = this.getViewportWarningOverlayTemplate_();
-    this.localizationService_ = Services.localizationForDoc(this.storyElement_);
+    this.localizationService_ = getLocalizationService(this.storyElement_);
 
     this.isBuilt_ = true;
     const root = this.win_.document.createElement('div');
diff --git a/extensions/amp-story/1.0/amp-story.js b/extensions/amp-story/1.0/amp-story.js
index c0ef90ea243b..716599edc5a6 100644
--- a/extensions/amp-story/1.0/amp-story.js
+++ b/extensions/amp-story/1.0/amp-story.js
@@ -107,6 +107,7 @@ import {escapeCssSelectorIdent} from '../../../src/css';
 import {findIndex, lastItem} from '../../../src/utils/array';
 import {getConsentPolicyState} from '../../../src/consent';
 import {getDetail} from '../../../src/event-helper';
+import {getLocalizationService} from './amp-story-localization-service';
 import {getMediaQueryService} from './amp-story-media-query-service';
 import {getMode} from '../../../src/mode';
 import {getState} from '../../../src/history';
@@ -358,7 +359,7 @@ export class AmpStory extends AMP.BaseElement {
     this.liveStoryManager_ = null;
 
     /** @private @const {!../../../src/service/localization.LocalizationService} */
-    this.localizationService_ = Services.localizationForDoc(this.element);
+    this.localizationService_ = getLocalizationService(this.element);
 
     this.localizationService_
       .registerLocalizedStringBundle('default', LocalizedStringsDefault)
@@ -2783,7 +2784,10 @@ export class AmpStory extends AMP.BaseElement {
    */
   static isBrowserSupported(win) {
     return Boolean(
-      win.CSS && win.CSS.supports && win.CSS.supports('display', 'grid')
+      win.CSS &&
+        win.CSS.supports &&
+        win.CSS.supports('display', 'grid') &&
+        win.CSS.supports('color', 'var(--test)')
     );
   }
 }
diff --git a/extensions/amp-story/1.0/animation.js b/extensions/amp-story/1.0/animation.js
index c06676a9cb1f..02435c0490cf 100644
--- a/extensions/amp-story/1.0/animation.js
+++ b/extensions/amp-story/1.0/animation.js
@@ -33,15 +33,11 @@ import {
   WebKeyframesDef,
 } from './animation-types';
 import {assertDoesNotContainDisplay, setStyles} from '../../../src/style';
-import {
-  childElementsByTag,
-  scopedQuerySelector,
-  scopedQuerySelectorAll,
-} from '../../../src/dom';
 import {dev, devAssert, user, userAssert} from '../../../src/log';
 import {escapeCssSelectorIdent} from '../../../src/css';
 import {getChildJsonConfig} from '../../../src/json';
 import {map, omit} from '../../../src/utils/object';
+import {scopedQuerySelector, scopedQuerySelectorAll} from '../../../src/dom';
 import {timeStrToMillis, unscaledClientRect} from './utils';
 
 /** @const {string} */
@@ -638,7 +634,9 @@ export class AnimationManager {
         )
         .concat(
           Array.prototype.map.call(
-            childElementsByTag(this.page_, 'amp-story-animation'),
+            this.page_.querySelectorAll(
+              'amp-story-animation[trigger=visibility]'
+            ),
             (el) =>
               this.createRunner_({
                 source: el,
@@ -717,6 +715,7 @@ export class AnimationManager {
       .then((webAnimationService) =>
         webAnimationService.createBuilder({
           scope: this.page_,
+          scaleByScope: true,
         })
       );
   }
diff --git a/extensions/amp-story/1.0/bookend/amp-story-bookend.js b/extensions/amp-story/1.0/bookend/amp-story-bookend.js
index f482965cb0c1..e5d4aaeab198 100644
--- a/extensions/amp-story/1.0/bookend/amp-story-bookend.js
+++ b/extensions/amp-story/1.0/bookend/amp-story-bookend.js
@@ -42,6 +42,7 @@ import {dev, devAssert, user, userAssert} from '../../../../src/log';
 import {dict} from '../../../../src/utils/object';
 import {getAmpdoc} from '../../../../src/service';
 import {getJsonLd} from '../jsonld';
+import {getLocalizationService} from '../amp-story-localization-service';
 import {getRequestService} from '../amp-story-request-service';
 import {isArray} from '../../../../src/types';
 import {renderAsElement} from '../simple-template';
@@ -629,7 +630,7 @@ export class AmpStoryBookend extends DraggableDrawer {
       return;
     }
 
-    const localizationService = Services.localizationForDoc(this.element);
+    const localizationService = getLocalizationService(this.element);
     if (!localizationService) {
       user().error(TAG, 'Unable to fetch localization service.');
       return;
diff --git a/extensions/amp-story/1.0/simple-template.js b/extensions/amp-story/1.0/simple-template.js
index 6e7ae3b14eca..e58cf765aec7 100644
--- a/extensions/amp-story/1.0/simple-template.js
+++ b/extensions/amp-story/1.0/simple-template.js
@@ -14,9 +14,9 @@
  * limitations under the License.
  */
 import {LocalizedStringId} from '../../../src/localized-strings'; // eslint-disable-line no-unused-vars
-import {Services} from '../../../src/services';
 import {createElementWithAttributes} from '../../../src/dom';
 import {devAssert} from '../../../src/log';
+import {getLocalizationService} from './amp-story-localization-service';
 import {hasOwn} from '../../../src/utils/object';
 import {isArray} from '../../../src/types';
 
@@ -83,9 +83,7 @@ function renderSingle(doc, elementDef) {
   const hasLocalizedTextContent = hasOwn(elementDef, 'localizedStringId');
   const hasLocalizedLabel = hasOwn(elementDef, 'localizedLabelId');
   if (hasLocalizedTextContent || hasLocalizedLabel) {
-    const localizationService = Services.localizationForDoc(
-      devAssert(doc.body)
-    );
+    const localizationService = getLocalizationService(devAssert(doc.body));
     devAssert(localizationService, 'Could not retrieve LocalizationService.');
 
     if (hasLocalizedTextContent) {
diff --git a/extensions/amp-story/1.0/test/test-amp-story-bookend.js b/extensions/amp-story/1.0/test/test-amp-story-bookend.js
index 1bc2d9d04a7f..d94e18bf7a3f 100644
--- a/extensions/amp-story/1.0/test/test-amp-story-bookend.js
+++ b/extensions/amp-story/1.0/test/test-amp-story-bookend.js
@@ -21,6 +21,7 @@ import {AnalyticsVariable, getVariableService} from '../variable-service';
 import {ArticleComponent} from '../bookend/components/article';
 import {CtaLinkComponent} from '../bookend/components/cta-link';
 import {LandscapeComponent} from '../bookend/components/landscape';
+import {LocalizationService} from '../../../../src/service/localization';
 import {PortraitComponent} from '../bookend/components/portrait';
 import {Services} from '../../../../src/services';
 import {StoryAnalyticsEvent, getAnalyticsService} from '../story-analytics';
@@ -126,6 +127,10 @@ describes.fakeWin('amp-story-bookend', {win: {location}, amp: true}, (env) => {
   beforeEach(() => {
     win = env.win;
     doc = win.document;
+    const localizationService = new LocalizationService(win.document.body);
+    env.sandbox
+      .stub(Services, 'localizationForDoc')
+      .returns(localizationService);
     storyElem = doc.createElement('amp-story');
     storyElem.appendChild(doc.createElement('amp-story-page'));
     doc.body.appendChild(storyElem);
diff --git a/extensions/amp-story/1.0/test/test-amp-story-consent.js b/extensions/amp-story/1.0/test/test-amp-story-consent.js
index 8867d55aef4c..b75381604ab5 100644
--- a/extensions/amp-story/1.0/test/test-amp-story-consent.js
+++ b/extensions/amp-story/1.0/test/test-amp-story-consent.js
@@ -16,6 +16,7 @@
 
 import {AmpStoryConsent} from '../amp-story-consent';
 import {AmpStoryStoreService, StateProperty} from '../amp-story-store-service';
+import {LocalizationService} from '../../../../src/service/localization';
 import {Services} from '../../../../src/services';
 import {registerServiceBuilder} from '../../../../src/service';
 
@@ -36,6 +37,10 @@ describes.realWin('amp-story-consent', {amp: true}, (env) => {
 
   beforeEach(() => {
     win = env.win;
+    const localizationService = new LocalizationService(win.document.body);
+    env.sandbox
+      .stub(Services, 'localizationForDoc')
+      .returns(localizationService);
     const storeService = new AmpStoryStoreService(win);
     registerServiceBuilder(win, 'story-store', function () {
       return storeService;
diff --git a/extensions/amp-story/1.0/test/test-amp-story-embedded-component.js b/extensions/amp-story/1.0/test/test-amp-story-embedded-component.js
index cf2315c486b6..8b6f6c203074 100644
--- a/extensions/amp-story/1.0/test/test-amp-story-embedded-component.js
+++ b/extensions/amp-story/1.0/test/test-amp-story-embedded-component.js
@@ -22,6 +22,7 @@ import {
 } from '../amp-story-store-service';
 import {AmpStoryEmbeddedComponent} from '../amp-story-embedded-component';
 import {EventType} from '../events';
+import {LocalizationService} from '../../../../src/service/localization';
 import {Services} from '../../../../src/services';
 import {StoryAnalyticsEvent} from '../story-analytics';
 import {addAttributesToElement} from '../../../../src/dom';
@@ -41,6 +42,11 @@ describes.realWin('amp-story-embedded-component', {amp: true}, (env) => {
   beforeEach(() => {
     win = env.win;
 
+    const localizationService = new LocalizationService(win.document.body);
+    env.sandbox
+      .stub(Services, 'localizationForDoc')
+      .returns(localizationService);
+
     // Making sure mutator tasks run synchronously.
     env.sandbox.stub(Services, 'mutatorForDoc').returns({
       mutateElement: (element, callback) => {
diff --git a/extensions/amp-story/1.0/test/test-amp-story-hint.js b/extensions/amp-story/1.0/test/test-amp-story-hint.js
index 73edd37955fc..3a07c2059cd8 100644
--- a/extensions/amp-story/1.0/test/test-amp-story-hint.js
+++ b/extensions/amp-story/1.0/test/test-amp-story-hint.js
@@ -16,6 +16,7 @@
 
 import {AmpStoryHint} from '../amp-story-hint';
 import {AmpStoryStoreService} from '../amp-story-store-service';
+import {LocalizationService} from '../../../../src/service/localization';
 import {Services} from '../../../../src/services';
 import {registerServiceBuilder} from '../../../../src/service';
 
@@ -29,7 +30,7 @@ describes.fakeWin('amp-story hint layer', {amp: true}, (env) => {
   beforeEach(() => {
     win = env.win;
 
-    const localizationService = Services.localizationForDoc(win.document.body);
+    const localizationService = new LocalizationService(win.document.body);
     env.sandbox
       .stub(Services, 'localizationForDoc')
       .returns(localizationService);
diff --git a/extensions/amp-story/1.0/test/test-amp-story-info-dialog.js b/extensions/amp-story/1.0/test/test-amp-story-info-dialog.js
index 4382d670ba24..1f4f5c66d210 100644
--- a/extensions/amp-story/1.0/test/test-amp-story-info-dialog.js
+++ b/extensions/amp-story/1.0/test/test-amp-story-info-dialog.js
@@ -24,6 +24,7 @@ import {
   InfoDialog,
   MOREINFO_VISIBLE_CLASS,
 } from '../amp-story-info-dialog';
+import {LocalizationService} from '../../../../src/service/localization';
 import {Services} from '../../../../src/services';
 import {registerServiceBuilder} from '../../../../src/service';
 
@@ -39,6 +40,11 @@ describes.realWin('amp-story-info-dialog', {amp: true}, (env) => {
 
   beforeEach(() => {
     win = env.win;
+    const localizationService = new LocalizationService(win.document.body);
+    env.sandbox
+      .stub(Services, 'localizationForDoc')
+      .returns(localizationService);
+
     storeService = new AmpStoryStoreService(win);
     embedded = true;
     registerServiceBuilder(win, 'story-store', function () {
diff --git a/extensions/amp-story/1.0/test/test-amp-story-page.js b/extensions/amp-story/1.0/test/test-amp-story-page.js
index 67d8d6377a69..655756350771 100644
--- a/extensions/amp-story/1.0/test/test-amp-story-page.js
+++ b/extensions/amp-story/1.0/test/test-amp-story-page.js
@@ -18,6 +18,7 @@ import {AmpDocSingle} from '../../../../src/service/ampdoc-impl';
 import {AmpStoryPage, PageState, Selectors} from '../amp-story-page';
 import {AmpStoryStoreService} from '../amp-story-store-service';
 import {Deferred} from '../../../../src/utils/promise';
+import {LocalizationService} from '../../../../src/service/localization';
 import {MediaType} from '../media-pool';
 import {Services} from '../../../../src/services';
 import {
@@ -48,7 +49,7 @@ describes.realWin('amp-story-page', {amp: true}, (env) => {
       }),
     };
 
-    const localizationService = Services.localizationForDoc(win.document.body);
+    const localizationService = new LocalizationService(win.document.body);
     env.sandbox
       .stub(Services, 'localizationForDoc')
       .returns(localizationService);
diff --git a/extensions/amp-story/1.0/test/test-amp-story-reaction-quiz.js b/extensions/amp-story/1.0/test/test-amp-story-reaction-quiz.js
index f4906bf0900b..f4bccadcbffa 100644
--- a/extensions/amp-story/1.0/test/test-amp-story-reaction-quiz.js
+++ b/extensions/amp-story/1.0/test/test-amp-story-reaction-quiz.js
@@ -16,9 +16,9 @@
 
 import {AmpStoryReactionQuiz} from '../amp-story-reaction-quiz';
 import {AmpStoryStoreService} from '../amp-story-store-service';
-import {AnalyticsVariable, getVariableService} from '../variable-service';
+import {LocalizationService} from '../../../../src/service/localization';
 import {Services} from '../../../../src/services';
-import {getAnalyticsService} from '../story-analytics';
+import {getMockReactionData} from './test-amp-story-reaction';
 import {getRequestService} from '../amp-story-request-service';
 import {registerServiceBuilder} from '../../../../src/service';
 
@@ -46,75 +46,6 @@ const populateQuiz = (win, quizElement, numPrompts = 1, numOptions = 4) => {
   quizElement.setAttribute('id', 'TEST_quizId');
 };
 
-/**
- * Populates the quiz with a prompt and three options.
- *
- * @param {Window} win
- * @param {AmpStoryQuiz} quiz
- */
-const populateStandardQuizContent = (win, quizElement) => {
-  populateQuiz(win, quizElement);
-};
-
-/**
- * Returns mock reaction data.
- *
- * @return {Object}
- */
-const getMockReactionData = () => {
-  return {
-    data: {
-      totalResponseCount: 10,
-      hasUserResponded: true,
-      responses: [
-        {
-          reactionValue: 0,
-          totalCount: 3,
-          selectedByUser: true,
-        },
-        {
-          reactionValue: 1,
-          totalCount: 3,
-          selectedByUser: false,
-        },
-        {
-          reactionValue: 2,
-          totalCount: 3,
-          selectedByUser: false,
-        },
-        {
-          reactionValue: 3,
-          totalCount: 1,
-          selectedByUser: false,
-        },
-      ],
-    },
-  };
-};
-
-/**
- * Generates a response given an array of counts.
- *
- * @param {Array<number>} responseCounts
- */
-const generateResponseDataFor = (responseCounts) => {
-  const response = {
-    totalResponseCount: responseCounts.reduce((a, b) => a + b, 0),
-    hasUserResponded: false,
-    responses: [],
-  };
-
-  responseCounts.forEach((count, index) => {
-    response.responses.push({
-      reactionValue: index,
-      totalCount: count,
-      selectedByUser: false,
-    });
-  });
-
-  return response;
-};
-
 describes.realWin(
   'amp-story-reaction-quiz',
   {
@@ -124,13 +55,16 @@ describes.realWin(
     let win;
     let ampStoryQuiz;
     let storyEl;
-    let analytics;
-    let analyticsVars;
     let requestService;
 
     beforeEach(() => {
       win = env.win;
 
+      const localizationService = new LocalizationService(win.document.body);
+      env.sandbox
+        .stub(Services, 'localizationForDoc')
+        .returns(localizationService);
+
       env.sandbox
         .stub(Services, 'cidForDoc')
         .resolves({get: () => Promise.resolve('cid')});
@@ -139,9 +73,6 @@ describes.realWin(
         'amp-story-reaction-quiz'
       );
       ampStoryQuizEl.getResources = () => win.__AMP_SERVICES.resources.obj;
-
-      analyticsVars = getVariableService(win);
-      analytics = getAnalyticsService(win, win.document.body);
       requestService = getRequestService(win, ampStoryQuizEl);
 
       const storeService = new AmpStoryStoreService(win);
@@ -163,16 +94,16 @@ describes.realWin(
     });
 
     it('should take the html and reformat it', () => {
-      populateStandardQuizContent(win, ampStoryQuiz.element);
+      populateQuiz(win, ampStoryQuiz.element);
       ampStoryQuiz.buildCallback();
-      expect(ampStoryQuiz.getQuizElement().children.length).to.equal(2);
+      expect(ampStoryQuiz.getRootElement().children.length).to.equal(2);
     });
 
     it('should structure the content in the quiz element', () => {
-      populateStandardQuizContent(win, ampStoryQuiz.element);
+      populateQuiz(win, ampStoryQuiz.element);
       ampStoryQuiz.buildCallback();
 
-      const quizContent = ampStoryQuiz.getQuizElement().children;
+      const quizContent = ampStoryQuiz.getRootElement().children;
       expect(quizContent[0]).to.have.class(
         'i-amphtml-story-reaction-quiz-prompt-container'
       );
@@ -195,38 +126,58 @@ describes.realWin(
 
     it('should throw an error with fewer than one prompt', () => {
       populateQuiz(win, ampStoryQuiz.element, 0);
-      expect(ampStoryQuiz.buildCallback).to.throw();
+      allowConsoleError(() => {
+        expect(() => {
+          ampStoryQuiz.buildCallback();
+        }).to.throw(
+          /The first child must be a heading element <h1>, <h2>, or <h3>/
+        );
+      });
     });
 
     it('should throw an error with more than one prompt', () => {
       populateQuiz(win, ampStoryQuiz.element, 2);
-      expect(ampStoryQuiz.buildCallback).to.throw();
+      allowConsoleError(() => {
+        expect(() => {
+          ampStoryQuiz.buildCallback();
+        }).to.throw(/Too many children/);
+      });
     });
 
     it('should throw an error with fewer than two options', () => {
       populateQuiz(win, ampStoryQuiz.element, 1, 1);
-      expect(ampStoryQuiz.buildCallback).to.throw();
+      allowConsoleError(() => {
+        expect(() => {
+          ampStoryQuiz.buildCallback();
+        }).to.throw(/Improper number of options/);
+      });
+    });
+
+    it('should not throw an error with three options and one prompt', () => {
+      populateQuiz(win, ampStoryQuiz.element, 1, 3);
+      expect(() => ampStoryQuiz.buildCallback()).to.not.throw();
     });
 
     it('should throw an error with more than four options', () => {
       populateQuiz(win, ampStoryQuiz.element, 1, 5);
-      expect(ampStoryQuiz.buildCallback).to.throw();
+      allowConsoleError(() => {
+        expect(() => {
+          ampStoryQuiz.buildCallback();
+        }).to.throw(/Improper number of options/);
+      });
     });
 
     it('should enter the post-interaction state on option click', async () => {
-      populateStandardQuizContent(win, ampStoryQuiz.element);
+      populateQuiz(win, ampStoryQuiz.element);
       ampStoryQuiz.buildCallback();
       await ampStoryQuiz.layoutCallback();
 
-      const quizElement = ampStoryQuiz.getQuizElement();
+      const quizElement = ampStoryQuiz.getRootElement();
       const quizOption = quizElement.querySelector(
         '.i-amphtml-story-reaction-quiz-option'
       );
 
-      quizOption.click();
-
-      // Microtask tick
-      await Promise.resolve();
+      await quizOption.click();
 
       expect(quizElement).to.have.class(
         'i-amphtml-story-reaction-post-selection'
@@ -236,80 +187,6 @@ describes.realWin(
       );
     });
 
-    it('should only record the first option response', async () => {
-      populateStandardQuizContent(win, ampStoryQuiz.element);
-      ampStoryQuiz.buildCallback();
-      await ampStoryQuiz.layoutCallback();
-
-      const quizElement = ampStoryQuiz.getQuizElement();
-      const quizOptions = quizElement.querySelectorAll(
-        '.i-amphtml-story-reaction-option'
-      );
-
-      quizOptions[0].click();
-      quizOptions[1].click();
-
-      // Microtask tick
-      await Promise.resolve();
-
-      expect(quizOptions[0]).to.have.class(
-        'i-amphtml-story-reaction-option-selected'
-      );
-      expect(quizOptions[1]).to.not.have.class(
-        'i-amphtml-story-reaction-option-selected'
-      );
-    });
-
-    it('should trigger an analytics event with the right variables on selection', async () => {
-      const trigger = env.sandbox.stub(analytics, 'triggerEvent');
-      populateStandardQuizContent(win, ampStoryQuiz.element);
-      ampStoryQuiz.buildCallback();
-      await ampStoryQuiz.layoutCallback();
-
-      const option = ampStoryQuiz
-        .getQuizElement()
-        .querySelector('.i-amphtml-story-reaction-quiz-option');
-
-      option.click();
-
-      // Microtask tick
-      await Promise.resolve();
-
-      expect(trigger).to.have.been.calledWith('story-reaction');
-
-      const variables = analyticsVars.get();
-      expect(variables[AnalyticsVariable.STORY_REACTION_ID]).to.equal(
-        'TEST_quizId'
-      );
-      expect(variables[AnalyticsVariable.STORY_REACTION_RESPONSE]).to.equal(0);
-      expect(variables[AnalyticsVariable.STORY_REACTION_TYPE]).to.equal(0);
-    });
-
-    it('should update the quiz when the user has already reacted', async () => {
-      // Fill the response to the requestService with mock reaction data.
-      env.sandbox
-        .stub(requestService, 'executeRequest')
-        .resolves(getMockReactionData());
-
-      ampStoryQuiz.element.setAttribute('endpoint', 'http://localhost:8000');
-
-      populateStandardQuizContent(win, ampStoryQuiz.element);
-      ampStoryQuiz.buildCallback();
-      await ampStoryQuiz.layoutCallback();
-
-      const quizElement = ampStoryQuiz.getQuizElement();
-      const quizOptions = quizElement.querySelectorAll(
-        '.i-amphtml-story-reaction-quiz-option'
-      );
-
-      expect(quizElement).to.have.class(
-        'i-amphtml-story-reaction-post-selection'
-      );
-      expect(quizOptions[0]).to.have.class(
-        'i-amphtml-story-reaction-option-selected'
-      );
-    });
-
     it('should handle the percentage pipeline', async () => {
       env.sandbox
         .stub(requestService, 'executeRequest')
@@ -317,55 +194,12 @@ describes.realWin(
 
       ampStoryQuiz.element.setAttribute('endpoint', 'http://localhost:8000');
 
-      populateStandardQuizContent(win, ampStoryQuiz.element);
+      populateQuiz(win, ampStoryQuiz.element);
       ampStoryQuiz.buildCallback();
       await ampStoryQuiz.layoutCallback();
 
-      const quizElement = ampStoryQuiz.getQuizElement();
-      const quizOptions = quizElement.querySelectorAll(
-        '.i-amphtml-story-reaction-quiz-option'
-      );
-
-      const percentageOption0 = quizOptions[0].querySelector(
-        '.i-amphtml-story-reaction-quiz-percentage-text'
-      );
-
-      expect(percentageOption0.textContent).to.equal('30%');
-
-      const percentageOption3 = quizOptions[3].querySelector(
-        '.i-amphtml-story-reaction-quiz-percentage-text'
-      );
-
-      expect(percentageOption3.textContent).to.equal('10%');
-    });
-
-    it('should preprocess percentages properly', () => {
-      const responseData1 = getMockReactionData()['data'];
-
-      const percentages1 = ampStoryQuiz.preprocessPercentages_(responseData1);
-
-      expect(percentages1).to.deep.equal([30, 30, 30, 10]);
-    });
-
-    it('should preprocess percentages preserving ties', () => {
-      const responseData2 = generateResponseDataFor([3, 3, 3]);
-      const percentages2 = ampStoryQuiz.preprocessPercentages_(responseData2);
-
-      expect(percentages2).to.deep.equal([33, 33, 33]);
-    });
-
-    it('should preprocess percentages preserving order', () => {
-      const responseData3 = generateResponseDataFor([255, 255, 245, 245]);
-      const percentages3 = ampStoryQuiz.preprocessPercentages_(responseData3);
-
-      expect(percentages3).to.deep.equal([26, 26, 24, 24]);
-    });
-
-    it('should preprocess percentages handling rounding edge cases', () => {
-      const responseData4 = generateResponseDataFor([335, 335, 330]);
-      const percentages4 = ampStoryQuiz.preprocessPercentages_(responseData4);
-
-      expect(percentages4).to.deep.equal([33, 33, 33]);
+      expect(ampStoryQuiz.getOptionElements()[0].innerText).to.equal('30%');
+      expect(ampStoryQuiz.getOptionElements()[3].innerText).to.equal('10%');
     });
   }
 );
diff --git a/extensions/amp-story/1.0/test/test-amp-story-reaction.js b/extensions/amp-story/1.0/test/test-amp-story-reaction.js
new file mode 100644
index 000000000000..1e88723cd704
--- /dev/null
+++ b/extensions/amp-story/1.0/test/test-amp-story-reaction.js
@@ -0,0 +1,250 @@
+/**
+ * Copyright 2019 The AMP HTML Authors. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS-IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import {AmpStoryReaction, ReactionType} from '../amp-story-reaction';
+import {AmpStoryStoreService} from '../amp-story-store-service';
+import {AnalyticsVariable, getVariableService} from '../variable-service';
+import {Services} from '../../../../src/services';
+import {dict} from '../../../../src/utils/object';
+import {getAnalyticsService} from '../story-analytics';
+import {getRequestService} from '../amp-story-request-service';
+import {htmlFor} from '../../../../src/static-template';
+import {registerServiceBuilder} from '../../../../src/service';
+
+/**
+ * Returns mock reaction data.
+ *
+ * @return {Object}
+ */
+export const getMockReactionData = () => {
+  return {
+    options: [
+      {
+        optionIndex: 0,
+        totalCount: 3,
+        selectedByUser: true,
+      },
+      {
+        optionIndex: 1,
+        totalCount: 3,
+        selectedByUser: false,
+      },
+      {
+        optionIndex: 2,
+        totalCount: 3,
+        selectedByUser: false,
+      },
+      {
+        optionIndex: 3,
+        totalCount: 1,
+        selectedByUser: false,
+      },
+    ],
+  };
+};
+
+class ReactionTest extends AmpStoryReaction {
+  constructor(element, options = 4) {
+    super(element, ReactionType.QUIZ);
+    this.options = options;
+  }
+
+  /** @override */
+  buildComponent(element) {
+    const html = htmlFor(element);
+    const root = html`<div class="container"></div>`;
+    const option = html`<span class="i-amphtml-story-reaction-option">1</span>`;
+    for (let i = 0; i < this.options; i++) {
+      const newOption = option.cloneNode();
+      newOption.optionIndex_ = i;
+      root.appendChild(newOption);
+    }
+    return root;
+  }
+}
+
+/**
+ * Generates a response given an array of counts.
+ *
+ * @param {Array<number>} responseCounts
+ */
+export const generateResponseDataFor = (responseCounts) => {
+  return responseCounts.map((count, index) =>
+    dict({
+      'optionIndex': index,
+      'totalCount': count,
+      'selectedByUser': false,
+    })
+  );
+};
+
+describes.realWin(
+  'amp-story-reaction',
+  {
+    amp: true,
+  },
+  (env) => {
+    let win;
+    let ampStoryReaction;
+    let storyEl;
+    let analytics;
+    let analyticsVars;
+    let requestService;
+
+    beforeEach(() => {
+      win = env.win;
+
+      env.sandbox
+        .stub(Services, 'cidForDoc')
+        .resolves({get: () => Promise.resolve('cid')});
+
+      const ampStoryReactionEl = win.document.createElement(
+        'amp-story-reaction'
+      );
+      ampStoryReactionEl.id = 'TEST_reactionId';
+      ampStoryReactionEl.getResources = () => win.__AMP_SERVICES.resources.obj;
+
+      analyticsVars = getVariableService(win);
+      analytics = getAnalyticsService(win, win.document.body);
+      requestService = getRequestService(win, ampStoryReactionEl);
+
+      const storeService = new AmpStoryStoreService(win);
+      registerServiceBuilder(win, 'story-store', function () {
+        return storeService;
+      });
+
+      storyEl = win.document.createElement('amp-story');
+      const storyPage = win.document.createElement('amp-story-page');
+      const gridLayer = win.document.createElement('amp-story-grid-layer');
+      gridLayer.appendChild(ampStoryReactionEl);
+      storyPage.appendChild(gridLayer);
+      storyEl.appendChild(storyPage);
+
+      win.document.body.appendChild(storyEl);
+      ampStoryReaction = new ReactionTest(ampStoryReactionEl, 4);
+
+      env.sandbox
+        .stub(ampStoryReaction, 'mutateElement')
+        .callsFake((fn) => fn());
+    });
+
+    it('should enter post-interaction state on option click', async () => {
+      ampStoryReaction.buildCallback();
+      await ampStoryReaction.layoutCallback();
+      await ampStoryReaction.getOptionElements()[0].click();
+      expect(ampStoryReaction.getRootElement()).to.have.class(
+        'i-amphtml-story-reaction-post-selection'
+      );
+      expect(ampStoryReaction.getOptionElements()[0]).to.have.class(
+        'i-amphtml-story-reaction-option-selected'
+      );
+    });
+
+    it('should only record first option selected', async () => {
+      ampStoryReaction.buildCallback();
+      await ampStoryReaction.layoutCallback();
+      await ampStoryReaction.getOptionElements()[0].click();
+      await ampStoryReaction.getOptionElements()[1].click();
+      expect(ampStoryReaction.getOptionElements()[0]).to.have.class(
+        'i-amphtml-story-reaction-option-selected'
+      );
+      expect(ampStoryReaction.getOptionElements()[1]).to.not.have.class(
+        'i-amphtml-story-reaction-option-selected'
+      );
+    });
+
+    it('should trigger an analytics event with the right variables on selection', async () => {
+      const trigger = env.sandbox.stub(analytics, 'triggerEvent');
+      ampStoryReaction.buildCallback();
+      await ampStoryReaction.layoutCallback();
+      await ampStoryReaction.getOptionElements()[1].click();
+      expect(trigger).to.have.been.calledWith('story-reaction');
+      const variables = analyticsVars.get();
+      expect(variables[AnalyticsVariable.STORY_REACTION_ID]).to.equal(
+        'TEST_reactionId'
+      );
+      expect(variables[AnalyticsVariable.STORY_REACTION_RESPONSE]).to.equal(1);
+      expect(variables[AnalyticsVariable.STORY_REACTION_TYPE]).to.equal(
+        ampStoryReaction.reactionType_
+      );
+    });
+
+    it('should update the quiz when the user has already reacted', async () => {
+      env.sandbox
+        .stub(requestService, 'executeRequest')
+        .resolves(getMockReactionData());
+      ampStoryReaction.element.setAttribute(
+        'endpoint',
+        'http://localhost:8000'
+      );
+      ampStoryReaction.buildCallback();
+      await ampStoryReaction.layoutCallback();
+
+      expect(ampStoryReaction.getRootElement()).to.have.class(
+        'i-amphtml-story-reaction-post-selection'
+      );
+      expect(ampStoryReaction.getOptionElements()[0]).to.have.class(
+        'i-amphtml-story-reaction-option-selected'
+      );
+    });
+
+    it('should throw error if percentages are not correctly passed', () => {
+      const responseData = dict({'wrongKey': []});
+      allowConsoleError(() => {
+        expect(() =>
+          ampStoryReaction.handleSuccessfulDataRetrieval_(responseData)
+        ).to.throw();
+      });
+    });
+
+    it('should preprocess percentages properly', () => {
+      const responseData1 = getMockReactionData()['options'];
+
+      const percentages1 = ampStoryReaction.preprocessPercentages_(
+        responseData1
+      );
+
+      expect(percentages1).to.deep.equal([30, 30, 30, 10]);
+    });
+
+    it('should preprocess percentages preserving ties', () => {
+      const responseData2 = generateResponseDataFor([3, 3, 3]);
+      const percentages2 = ampStoryReaction.preprocessPercentages_(
+        responseData2
+      );
+
+      expect(percentages2).to.deep.equal([33, 33, 33]);
+    });
+
+    it('should preprocess percentages preserving order', () => {
+      const responseData3 = generateResponseDataFor([255, 255, 245, 245]);
+      const percentages3 = ampStoryReaction.preprocessPercentages_(
+        responseData3
+      );
+
+      expect(percentages3).to.deep.equal([26, 26, 24, 24]);
+    });
+
+    it('should preprocess percentages handling rounding edge cases', () => {
+      const responseData4 = generateResponseDataFor([335, 335, 330]);
+      const percentages4 = ampStoryReaction.preprocessPercentages_(
+        responseData4
+      );
+
+      expect(percentages4).to.deep.equal([33, 33, 33]);
+    });
+  }
+);
diff --git a/extensions/amp-story/1.0/test/test-amp-story-system-layer.js b/extensions/amp-story/1.0/test/test-amp-story-system-layer.js
index b0c6b923479a..dec43610bca1 100644
--- a/extensions/amp-story/1.0/test/test-amp-story-system-layer.js
+++ b/extensions/amp-story/1.0/test/test-amp-story-system-layer.js
@@ -13,11 +13,13 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+
 import {
   Action,
   AmpStoryStoreService,
   StateProperty,
 } from '../amp-story-store-service';
+import {LocalizationService} from '../../../../src/service/localization';
 import {ProgressBar} from '../progress-bar';
 import {Services} from '../../../../src/services';
 import {SystemLayer} from '../amp-story-system-layer';
@@ -35,6 +37,11 @@ describes.fakeWin('amp-story system layer', {amp: true}, (env) => {
   beforeEach(() => {
     win = env.win;
 
+    const localizationService = new LocalizationService(win.document.body);
+    env.sandbox
+      .stub(Services, 'localizationForDoc')
+      .returns(localizationService);
+
     storeService = new AmpStoryStoreService(win);
     registerServiceBuilder(win, 'story-store', function () {
       return storeService;
diff --git a/extensions/amp-story/1.0/test/test-amp-story.js b/extensions/amp-story/1.0/test/test-amp-story.js
index 3e09a43b2cc7..ea1041f802cb 100644
--- a/extensions/amp-story/1.0/test/test-amp-story.js
+++ b/extensions/amp-story/1.0/test/test-amp-story.js
@@ -29,6 +29,7 @@ import {AmpStoryBookend} from '../bookend/amp-story-bookend';
 import {AmpStoryConsent} from '../amp-story-consent';
 import {CommonSignals} from '../../../../src/common-signals';
 import {Keys} from '../../../../src/utils/key-codes';
+import {LocalizationService} from '../../../../src/service/localization';
 import {MediaType} from '../media-pool';
 import {PageState} from '../amp-story-page';
 import {PaginationButtons} from '../pagination-buttons';
@@ -117,9 +118,7 @@ describes.realWin(
       win.document.title = 'Story';
       env.ampdoc.defaultView = env.win;
 
-      const localizationService = Services.localizationForDoc(
-        win.document.body
-      );
+      const localizationService = new LocalizationService(win.document.body);
       env.sandbox
         .stub(Services, 'localizationForDoc')
         .returns(localizationService);
diff --git a/extensions/amp-story/1.0/test/test-animation.js b/extensions/amp-story/1.0/test/test-animation.js
index 466b37916cb6..165db2bbc481 100644
--- a/extensions/amp-story/1.0/test/test-animation.js
+++ b/extensions/amp-story/1.0/test/test-animation.js
@@ -458,6 +458,7 @@ describes.realWin('amp-story animations', {}, (env) => {
         webAnimationService.createBuilder.withArgs(
           env.sandbox.match({
             scope: page,
+            scaleByScope: true,
           })
         )
       ).to.have.been.calledOnce;
@@ -495,10 +496,10 @@ describes.realWin('amp-story animations', {}, (env) => {
 
       const page = html`
         <div>
-          <amp-story-animation ref="spec1source">
+          <amp-story-animation trigger="visibility" ref="spec1source">
             <script type="application/json"></script>
           </amp-story-animation>
-          <amp-story-animation ref="spec2source">
+          <amp-story-animation trigger="visibility" ref="spec2source">
             <script type="application/json"></script>
           </amp-story-animation>
         </div>
@@ -646,6 +647,7 @@ describes.realWin('amp-story animations', {}, (env) => {
             id="animated-fourth"
             ref="animatedFourth"
             animate-in-after="animated-third"
+            trigger="visibility"
           >
             <script type="application/json">
               {}
diff --git a/extensions/amp-story/1.0/test/test-full-bleed-animations.js b/extensions/amp-story/1.0/test/test-full-bleed-animations.js
index 2886fdf6859e..deb51e2b79c1 100644
--- a/extensions/amp-story/1.0/test/test-full-bleed-animations.js
+++ b/extensions/amp-story/1.0/test/test-full-bleed-animations.js
@@ -20,6 +20,7 @@
 
 import {AmpStory} from '../amp-story';
 import {AmpStoryStoreService} from '../amp-story-store-service';
+import {LocalizationService} from '../../../../src/service/localization';
 import {Services} from '../../../../src/services';
 import {
   calculateTargetScalingFactor,
@@ -58,9 +59,7 @@ describes.realWin(
         };
       });
 
-      const localizationService = Services.localizationForDoc(
-        win.document.body
-      );
+      const localizationService = new LocalizationService(win.document.body);
       env.sandbox
         .stub(Services, 'localizationForDoc')
         .returns(localizationService);
diff --git a/extensions/amp-story/1.0/test/test-live-story-manager.js b/extensions/amp-story/1.0/test/test-live-story-manager.js
index 2a264ef7b4ab..0e535c8ac6e4 100644
--- a/extensions/amp-story/1.0/test/test-live-story-manager.js
+++ b/extensions/amp-story/1.0/test/test-live-story-manager.js
@@ -19,6 +19,7 @@ import {AmpStory} from '../amp-story';
 import {AmpStoryPage} from '../amp-story-page';
 import {CommonSignals} from '../../../../src/common-signals';
 import {LiveStoryManager} from '../live-story-manager';
+import {LocalizationService} from '../../../../src/service/localization';
 import {Services} from '../../../../src/services';
 import {addAttributesToElement} from '../../../../src/dom';
 import {registerServiceBuilder} from '../../../../src/service';
@@ -59,9 +60,7 @@ describes.realWin(
     beforeEach(async () => {
       win = env.win;
 
-      const localizationService = Services.localizationForDoc(
-        win.document.body
-      );
+      const localizationService = new LocalizationService(win.document.body);
       env.sandbox
         .stub(Services, 'localizationForDoc')
         .returns(localizationService);
diff --git a/extensions/amp-stream-gallery/0.1/amp-stream-gallery.js b/extensions/amp-stream-gallery/0.1/amp-stream-gallery.js
index c598671619b6..376afaa58e18 100644
--- a/extensions/amp-stream-gallery/0.1/amp-stream-gallery.js
+++ b/extensions/amp-stream-gallery/0.1/amp-stream-gallery.js
@@ -268,6 +268,11 @@ class AmpStreamGallery extends AMP.BaseElement {
     return isLayoutSizeDefined(layout);
   }
 
+  /** @override */
+  prerenderAllowed() {
+    return true;
+  }
+
   /** @override */
   buildCallback() {
     userAssert(
diff --git a/extensions/amp-subscriptions-google/0.1/amp-subscriptions-google.js b/extensions/amp-subscriptions-google/0.1/amp-subscriptions-google.js
index 3d0ff75ee13a..1e5e0bd5631b 100644
--- a/extensions/amp-subscriptions-google/0.1/amp-subscriptions-google.js
+++ b/extensions/amp-subscriptions-google/0.1/amp-subscriptions-google.js
@@ -579,6 +579,12 @@ export class GoogleSubscriptionsPlatform {
         if (messageTextColor) {
           opts.messageTextColor = messageTextColor;
         }
+        const messageNumber = element.getAttribute(
+          'subscriptions-message-number'
+        );
+        if (messageNumber) {
+          opts.messageNumber = messageNumber;
+        }
         this.runtime_.attachSmartButton(element, opts, () => {});
         break;
       default:
diff --git a/extensions/amp-subscriptions-google/0.1/test/test-amp-subscriptions-google.js b/extensions/amp-subscriptions-google/0.1/test/test-amp-subscriptions-google.js
index e7b463e7f504..515b9775e4ff 100644
--- a/extensions/amp-subscriptions-google/0.1/test/test-amp-subscriptions-google.js
+++ b/extensions/amp-subscriptions-google/0.1/test/test-amp-subscriptions-google.js
@@ -673,6 +673,20 @@ describes.realWin('amp-subscriptions-google', {amp: true}, (env) => {
     });
   });
 
+  it('should use message number', () => {
+    const elem = env.win.document.createElement('div');
+    const attachStub = env.sandbox.stub(platform.runtime_, 'attachSmartButton');
+    elem.textContent = 'some html';
+    elem.setAttribute('subscriptions-lang', 'en');
+    elem.setAttribute('subscriptions-message-number', 1);
+    platform.decorateUI(elem, 'subscribe-smartbutton');
+    expect(attachStub).to.be.calledWith(elem, {
+      lang: 'en',
+      theme: 'light',
+      messageNumber: '1', // Message is 'Subscribe with just a few taps' on smartbox button.
+    });
+  });
+
   it('should throw if smartButton language is missing', () => {
     //expectAsyncConsoleError(/must have a language attrbiute​​​/);
     const elem = env.win.document.createElement('div');
diff --git a/extensions/amp-subscriptions/amp-subscriptions.md b/extensions/amp-subscriptions/amp-subscriptions.md
index 5d04a296c455..e9edf7d96995 100644
--- a/extensions/amp-subscriptions/amp-subscriptions.md
+++ b/extensions/amp-subscriptions/amp-subscriptions.md
@@ -234,7 +234,7 @@ The properties in the "local" service are (remote mode):
 - "pingbackUrl" - the pingback endpoint URL.
 - "actions" - a named map of action URLs. At a minimum there must be two actions specified: "login" and "subscribe".
 
-In iframe mode the `authorzationUrl` and `pingbackUrl` are deleted
+In iframe mode the `authorizationUrl` and `pingbackUrl` are deleted
 and replaced by:
 
 - "iframeSrc" - publisher supplied iframe
diff --git a/package.json b/package.json
index 6c26b9b24744..9a550520993f 100644
--- a/package.json
+++ b/package.json
@@ -41,7 +41,7 @@
     "@jest/core": "26.0.1",
     "@types/minimist": "1.2.0",
     "acorn-globals": "6.0.0",
-    "amphtml-validator": "1.0.30",
+    "amphtml-validator": "1.0.31",
     "ansi-colors": "4.1.1",
     "ast-replace": "1.1.3",
     "atob": "2.1.2",
@@ -73,29 +73,29 @@
     "enzyme": "3.11.0",
     "enzyme-adapter-preact-pure": "2.2.0",
     "escodegen": "1.14.1",
-    "eslint": "6.8.0",
+    "eslint": "7.0.0",
     "eslint-config-prettier": "6.11.0",
     "eslint-plugin-chai-expect": "2.1.0",
     "eslint-plugin-eslint-plugin": "2.2.1",
     "eslint-plugin-google-camelcase": "0.0.2",
     "eslint-plugin-jasmine": "4.1.1",
-    "eslint-plugin-jsdoc": "24.0.2",
+    "eslint-plugin-jsdoc": "24.0.6",
     "eslint-plugin-local": "1.0.0",
     "eslint-plugin-notice": "0.9.10",
     "eslint-plugin-prettier": "3.1.3",
     "eslint-plugin-react": "7.19.0",
-    "eslint-plugin-react-hooks": "3.0.0",
+    "eslint-plugin-react-hooks": "4.0.0",
     "eslint-plugin-sort-imports-es6-autofix": "0.5.0",
     "eslint-plugin-sort-requires": "2.1.0",
     "event-stream": "4.0.1",
     "express": "4.17.1",
     "fancy-log": "1.3.3",
-    "fetch-mock": "9.4.0",
+    "fetch-mock": "9.5.1",
     "formidable": "1.2.2",
     "fs-extra": "9.0.0",
     "fuse.js": "5.2.3",
     "globby": "11.0.0",
-    "google-closure-compiler": "20200426.0.0",
+    "google-closure-compiler": "20200504.0.0",
     "gulp": "4.0.2",
     "gulp-append-prepend": "1.0.8",
     "gulp-ava": "3.0.0",
@@ -124,7 +124,7 @@
     "jsdom": "16.2.2",
     "json-stable-stringify": "1.0.1",
     "json5": "2.1.3",
-    "karma": "5.0.4",
+    "karma": "5.0.5",
     "karma-browserify": "7.0.0",
     "karma-chai": "0.1.0",
     "karma-chrome-launcher": "3.1.0",
@@ -158,7 +158,7 @@
     "path": "0.12.7",
     "pkg-up": "3.1.0",
     "plugin-error": "1.0.1",
-    "postcss": "7.0.29",
+    "postcss": "7.0.30",
     "postcss-import": "12.0.1",
     "posthtml": "0.13.0",
     "prettier": "2.0.5",
diff --git a/spec/amp-framework-hosting.md b/spec/amp-framework-hosting.md
new file mode 100644
index 000000000000..740100eb84ea
--- /dev/null
+++ b/spec/amp-framework-hosting.md
@@ -0,0 +1,324 @@
+# Hosting the AMP framework
+
+You can host the AMP framework and components from your own server or CDN. This feature has a number of applications. For example, you can...
+
+- set a release cadence that matches your development cycle.
+- deliver the AMP framework in regions where `cdn.ampproject.org` may not be available.
+- serve AMP pages and the framework from the same host, potentially improving content delivery times.
+- test and demonstrate changes to the framework or components.
+
+The AMP Project is looking into options for [validation](https://amp.dev/documentation/guides-and-tutorials/learn/validation-workflow/validate_amp/) of AMP pages that use an AMP framework hosted outside of `cdn.ampproject.org` ([#27546](https://github.com/ampproject/amphtml/issues/27546)). As of April 2020, these AMP pages do not pass validation.
+
+## Versioning
+
+This document makes frequent use of the terms "version" and "runtime version (rtv)". These two versions are slightly different. When the AMP framework is built, it is assigned a 13-digit _version_. When the AMP framework is served, a config number prefixes the version, resulting in a 15-digit _runtime version_. The build system and runtime enforce these version formats.
+
+Note: The _version_ (sometimes referred to as the "AMP version number") and _runtime version_ are often confused with each other. When it matters, be explicit about the version to which you're referring by indicating 13- or 15-digits.
+
+When the AMP framework is built (either by you or by the AMP Project), a 13-digit date-based version is automatically assigned. You can find this version in `version.txt` at the root of the AMP framework distribution. Then, the easiest route to hosting the AMP framework is to prefix this version with `01` to create a 15-digit runtime version, where `01` indicates a stable release.
+
+A more complete picture of the conventions adopted by the AMP Project for the version and runtime version is below. This is more than you need to get started with hosting the AMP framework, but serves as a good reference in case you want to expand your hosting capabilities.
+
+- Version ([#16631](https://github.com/ampproject/amphtml/pull/16631) and [#27848](https://github.com/ampproject/amphtml/pull/27848)): the commit time of the last commit in the active branch
+
+  ```
+  TZ=UTC git log -1 --pretty="%cd" --date=format-local:%y%m%d%H%M
+  ```
+
+  with three trailing digits indicating the number of cherry-picks included in the release. This version corresponds to the release versions found on [github.com/ampproject/amphtml/releases](https://github.com/ampproject/amphtml/releases).
+
+  Note: Prior to 2020-04-25, the version was based on date/time format `%y%m%d%H%M%S` with a single trailing digit – typically `0`, but could be change arbitrarily.
+
+- Runtime version (rtv): the version prefixed by a 2-digit config code:
+
+  - Experimental: `00`
+  - Stable: `01`
+  - Control: `02`
+  - Beta: `03`
+  - Nightly: `04`
+  - Nightly-Control: `05`
+  - AMP Experiments: `10`, `11`, `12`
+  - INABOX Control and Experiments: `20`, `21`, `22`, `23`, `24`, `25`
+
+The runtime version is found in URLs and is reported in the console of browser inspectors when an AMP page loads. For example, runtime version `012004041903580` is stable version `2004041903580`.
+
+## Acquire the AMP framework
+
+The AMP framework can be built from source or downloaded pre-built. Building the framework yourself gives you the flexibility of modifying the framework for your needs and deploying changes on your own release cycle. Downloading a pre-built framework means you'll be using an unmodified release, vetted by the AMP Project for distribution.
+
+### Option 1: Build the framework yourself
+
+Refer to the [Developing in AMP](https://github.com/ampproject/amphtml/blob/master/contributing/DEVELOPING.md) guide to familiarize yourself with building and testing the AMP framework. Once you are comfortable with the build system, a few small changes will customize the framework to run from your host.
+
+#### Update URLs config
+
+When AMP is built, several scripts are prepended with an `AMP_CONFIG` environment variable (object) containing basic information like: runtime version, config type, experiment enable/disable status, etc. This object can be customized at build time to inform the runtime where the framework is hosted. See [build-system/global-configs/README.md](https://github.com/ampproject/amphtml/tree/master/build-system/global-configs#custom-configjson) for information about the `custom-config.json` overlay.
+
+Create JSON file `build-system/global-configs/custom-config.json` with the following contents:
+
+```
+{
+  "cdnUrl": "https://example.com/amp-framework",
+  "geoApiUrl": "https://example.com/geo-api"
+}
+```
+
+where
+
+- `cdnUrl` is the base URL to your AMP framework. Defaults to `https://cdn.ampproject.org`.
+- `geoApiUrl` (optional) is your amp-geo fallback API URL. This API is described in section [amp-geo hotpatching](#amp-geo-hotpatching). Defaults to `null`.
+
+Important: `build-system/global-configs/custom-config.json` is not part of checked-in source. If it exists, it _always_ applies at build time, overlaying the active config. Don't forget about it! You can verify the overlay applies by looking for log line `Overlaid config with custom-config.json` during the build process.
+
+#### Build the framework
+
+Build an AMP release with
+
+```
+gulp dist
+```
+
+The built framework can be found in directory `dist`. The version assigned to the build is in `dist/version.txt` and a listing of all files included in build is in `dist/files.txt`. The framework is ready to be moved to and served from your host.
+
+If you have advanced hosting capabilities or would like to manually assign a version, `gulp dist` accepts these flags (among others):
+
+- `--config`: Indicate the release type, production (`prod`) or canary (`canary`). Defaults to `prod`.
+- `--version_override`: Assign a version to the distribution. The version must consist of 13-digits. Defaults to the latest git commit time of the active branch.
+- `--sourcemap_url`: Provide the base URL for JavaScript source map links. This URL should contain placeholder `{version}` that will be replaced with the actual version when the AMP framework is built, for example `https://raw.githubusercontent.com/<github-username>/amphtml/{version}/`. Defaults to `https://raw.githubusercontent.com/ampproject/amphtml/{version}/`.
+
+### Option 2: Download the framework with an AMP Toolbox tool
+
+[AMP Toolbox](https://github.com/ampproject/amp-toolbox) has both a Node.js module and a command line tool that will fetch a complete AMP framework from `cdn.ampproject.org`. Pick the tool best suited to your release workflow.
+
+- [@ampproject/toolbox-runtime-fetch](https://github.com/ampproject/amp-toolbox/tree/master/packages/runtime-fetch) - Node.js module
+- [@ampproject/toolbox-cli](https://github.com/ampproject/amp-toolbox/tree/master/packages/cli) - command line interface
+
+### Option 3: Manually copy the framework from cdn.ampproject.org
+
+The AMP framework can be copied from `cdn.ampproject.org`. The latest weekly release is always served from the root of `cdn.ampproject.org`. All [non-deprecated releases](https://github.com/ampproject/amphtml/blob/master/spec/amp-versioning-policy.md#version-deprecations) can be found in versioned URLs: `cdn.ampproject.org/rtv/<rtv>`, where `<rtv>` is the runtime version.
+
+Note: The AMP Project is looking into options for packaging releases ([#27726](https://github.com/ampproject/amphtml/issues/27726)).
+
+#### Copy files
+
+A listing of files in each release can be found in `files.txt` at the root of the framework distribution. For example, the files included in the current weekly release are listed in [cdn.ampproject.org/files.txt](https://cdn.ampproject.org/files.txt). Use your favorite HTTP client to download all of the files in `files.txt`, retaining path structures.
+
+#### Undo amp-geo dynamic modification
+
+When you request `amp-geo-0.1.js` from `cdn.ampproject.org` using an HTTP client, the CDN detects the country where the request originated and patches `amp-geo-0.1.js` on-the-fly. This patch needs to be reversed to ensure users are not all assigned the same country when amp-geo loads.
+
+When `cdn.ampproject.org` serves `amp-geo-0.1.js`, it replaces string `{{AMP_ISO_COUNTRY_HOTPATCH}}` with an ISO 3166-1 country code or an ISO 3166-2 country-subdivision code, followed by enough spaces to maintain the length of the string being replaced. Reversal of this patch can be accomplished by a RegEx replacement: search for `/ {28}|[a-z]{2} {26}|[a-z]{2} [a-z]{2}-[a-z0-9]{1,3} {19,21}/i` and replace with `{{AMP_ISO_COUNTRY_HOTPATCH}}`.
+
+In addition to `amp-geo-0.1.js`, you may find module JS (`.mjs`) and unversioned (`amp-geo-latest.js`) variants of the same file. The same RegEx replacement should be performed in these files as well.
+
+## Modify AMP pages
+
+AMP pages should be updated to fetch all scripts from your host. For example,
+
+```
+<script async src="https://cdn.ampproject.org/v0.js"></script>
+<script async custom-element="amp-carousel" src="https://cdn.ampproject.org/v0/amp-carousel-0.1.js"></script>
+```
+
+becomes
+
+```
+<script async src="https://example.com/amp/v0.js"></script>
+<script async custom-element="amp-carousel" src="https://example.com/amp/v0/amp-carousel-0.1.js"></script>
+```
+
+Versioned URLs are also possible and discussed in section [Serve the AMP framework](#serve-the-amp-framework).
+
+Important: All scripts must come from the same origin. Fetching scripts from multiple origins is not supported and can lead to unpredictable end user experiences.
+
+### Meta tags
+
+If you opted to download the AMP framework, then it was built under the assumption that it would be hosted from its default location, `cdn.ampproject.org`. While `<script>` tags included in the `<head>` of your AMP pages will download from the URLs specified in their `src` attributes, dynamically loaded components like `amp-loader-0.1.js` will download from `cdn.ampproject.org`. Mixing a self-hosted AMP runtime with AMP components from `cdn.ampproject.org` is not supported and can lead to unpredictable end user experiences.
+
+The default host used by the AMP runtime can be updated by including the following `<meta>` tag in the `<head>` of your AMP pages:
+
+```
+<meta name="runtime-host" content="...">
+```
+
+where the `content` attribute should contain a URL to your hosted AMP framework. Similarly, an amp-geo fallback API URL (described in section [amp-geo hotpatching](#amp-geo-hotpatching)) can be defined with the following `<meta>` tag:
+
+```
+<meta name="amp-geo-api" content="...">
+```
+
+In each case, the value of the `content` attribute should be an absolute, HTTPS URL. Importantly, **these meta tags must appear before the first `<script>` tag**. For example, if your AMP framework is hosted at `https://example.com/amp`, then your `<head>` should look similar to the following:
+
+```
+<head>
+  ...
+  <!-- This instructs the AMP runtime to update its default host -->
+  <meta name="runtime-host" content="https://example.com/amp">
+
+  <!-- (Optional) This provides a fallback API for amp-geo -->
+  <meta name="amp-geo-api" content="https://example.com/geo/get-country">
+
+  <!-- All scripts appear after the above meta tags -->
+  <script async src="https://example.com/amp/v0.js"></script>
+  <script async custom-element="amp-geo" src="https://example.com/amp/v0/amp-geo-0.1.js"></script>
+</head>
+```
+
+## Serve the AMP framework
+
+Depending on your hosting capabilities and goals, there are several options to consider when serving the AMP framework.
+
+### URLs
+
+When the AMP runtime is initialized, all components are verified to belong to the same AMP framework version as the runtime itself. This affects components that have already downloaded as well as components that are downloaded dynamically, like amp-loader. Dynamic components and components with incorrect versions are (re-)downloaded from an rtv-specific path. This has consequences on how you choose to host the runtime.
+
+#### Versioned URLs
+
+The simplest option for hosting the AMP framework is to host it from an rtv-specific path. For example, consider AMP framework host `https://example.com/amp`. Stable version `2002290616360` corresponds to runtime version `012002290616360` and should be hosted from `https://example.com/amp/rtv/012002290616360`. In this case, AMP meta and script URLs would look like the following:
+
+```
+<meta name="runtime-host" content="https://example.com/amp"> <!-- not rtv-specific -->
+<script async src="https://example.com/amp/rtv/012002290616360/v0.js"></script>
+<script async custom-element="amp-geo" src="https://example.com/amp/rtv/012002290616360/v0/amp-geo-0.1.js"></script>
+```
+
+If hosting a single AMP framework version is your end goal, then you can update your AMP pages to download the runtime and components from your host and skip to section [amp-geo hotpatching](#amp-geo-hotpatching). If you expect to update the AMP framework regularly, then updating rtv-specific URLs in AMP pages could be cumbersome. See the next section, [Versionless URLs](#versionless-urls), for a solution.
+
+#### Versionless URLs
+
+The AMP Project has a [weekly release channel](https://amp.dev/documentation/guides-and-tutorials/learn/spec/release-schedule/#weekly), sometimes referred to as the "evergreen" release channel. AMP pages utilize this channel by including versionless URLs to AMP scripts and styles. This is relatively easy to accomplish when hosting the AMP framework yourself. The key is to ensure that the AMP framework hosted from versionless URLs is _also_ available from rtv-specific URLs. This suggests an update strategy: first make a new AMP framework version available from rtv-specific URLs and _then_ update the AMP framework available from versionless URLs. For example, if stable AMP framework version `2002290616360` is available from `https://example.com/amp`, then it must also be available from `https://example.com/amp/rtv/012002290616360`. In this case, AMP meta and script URLs would look like the following:
+
+```
+<meta name="runtime-host" content="https://example.com/amp">
+<script async src="https://example.com/amp/v0.js"></script>
+<script async custom-element="amp-geo" src="https://example.com/amp/v0/amp-geo-0.1.js"></script>
+```
+
+If you inspect the DOM after an AMP page loads, you'll notice additional components are dynamically loaded by the runtime and use versioned URLs, for example
+
+```
+<script async custom-element="amp-auto-lightbox" data-script="amp-auto-lightbox" i-amphtml-inserted crossorigin="anonymous" src="https://example.com/amp/rtv/012002290616360/v0/amp-auto-lightbox-0.1.js"></script>
+```
+
+### Metadata
+
+The AMP Project hosts a metadata endpoint at [cdn.ampproject.org/rtv/metadata](https://cdn.ampproject.org/rtv/metadata) that returns information on current releases. Hosting this endpoint yourself is optional, but may be useful if you use [AMP Toolbox](https://github.com/ampproject/amp-toolbox):
+
+- [@ampproject/toolbox-runtime-version](https://github.com/ampproject/amp-toolbox/tree/master/packages/runtime-version) uses the data to determine the latest AMP framework version available.
+- [@ampproject/toolbox-optimizer](https://github.com/ampproject/amp-toolbox/tree/master/packages/optimizer) uses the data to identify the boilerplate CSS that should be included in optimized AMP pages.
+- [@ampproject/toolbox-runtime-fetch](https://github.com/ampproject/amp-toolbox/tree/master/packages/runtime-fetch) uses the data to identify an rtv-specific path from which the framework should be downloaded.
+
+Consider the following sample from [cdn.ampproject.org/rtv/metadata](https://cdn.ampproject.org/rtv/metadata), most JSON properties are optional:
+
+```
+{
+  "ampRuntimeVersion": "012002192257490",
+  "ampCssUrl": "https://cdn.ampproject.org/rtv/012002192257490/v0.css",
+  "canaryPercentage": "0.005",
+  "diversions": ["002002251816300", "032002251816300", "022002192257490"],
+  "ltsRuntimeVersion": "012002191527100",
+  "ltsCssUrl": "https://cdn.ampproject.org/rtv/012002191527100/v0.css"
+}
+```
+
+The properties are defined as follows:
+
+- `ampRuntimeVersion` (required) is the current stable runtime version of the AMP framework.
+- `ampCssUrl` (optional) is a URL to the boilerplate CSS for the current stable runtime version.
+- `canaryPercentage` (optional) indicates the fraction of users who receive the experimental runtime version of the AMP framework instead of the current stable runtime version.
+- `diversions` (optional) lists active non-stable runtime versions.
+- `ltsRuntimeVersion` (optional) is the current [long-term stable](https://github.com/ampproject/amphtml/blob/master/contributing/lts-release.md) runtime version.
+- `ltsCssUrl` (optional) is a URL to the boilerplate CSS for the current long-term stable runtime version.
+
+### amp-geo hotpatching
+
+[amp-geo](https://amp.dev/documentation/components/amp-geo/) requires special attention when hosting the AMP framework. When `cdn.ampproject.org` serves any of `amp-geo-0.1.js`, `amp-geo-0.1.mjs`, `amp-geo-latest.js`, or `amp-geo-latest.mjs`, it detects the country and subdivision where the request originated and replaces string `{{AMP_ISO_COUNTRY_HOTPATCH}}` with region data and enough trailing spaces to maintain the original string length. Ideally, when hosting the AMP framework, your content distribution platform would perform the same manipulation. The logic is as follows:
+
+- If country could not be determined, substitute 28 spaces:
+  ```
+  Before: "{{AMP_ISO_COUNTRY_HOTPATCH}}"
+  After:  "                            "
+  ```
+- If country could be determined, substitute the ISO 3166-1 alpha-2 country code followed by 26 spaces:
+  ```
+  Before: "{{AMP_ISO_COUNTRY_HOTPATCH}}"
+  After:  "xx                          "
+  ```
+  where `xx` is the country code (e.g. `de` for Germany).
+- If country and subdivision could be determined and are exactly `us` (United States) and `ca` (California), respectively (this is the only subdivision supported by amp-geo as of this writing), substitute the ISO 3166-1 alpha-2 country code _and_ the ISO 3166-2 country-subdivision code followed by 20 spaces:
+  ```
+  Before: "{{AMP_ISO_COUNTRY_HOTPATCH}}"
+  After:  "us us-ca                    "
+  ```
+
+#### amp-geo fallback API
+
+If location detection and file modification at time of delivery are not possible, amp-geo supports use of an API to fetch the user's country at run time. Be aware that usage of an API for this feature increases the chances of visible content or style shifts due to the delay of an additional network request. The AMP Project does not provide this API service; you need to supply your own API. Two example providers (not a comprehensive list) that offer IP-to-country databases from which an API could be created include [MaxMind](https://www.maxmind.com) and [IP2Location](https://www.ip2location.com/).
+
+The API must meet the following requirements:
+
+- Satisfy [CORS security in AMP](https://github.com/ampproject/amphtml/blob/master/spec/amp-cors-requests.md)
+- Be secure (HTTPS)
+- Return `application/json` content conforming to the following schema:
+  ```
+  {
+    "$schema": "http://json-schema.org/draft-07/schema#",
+    "type": "object",
+    "properties": {
+      "country": {
+        "type": "string",
+        "title": "ISO 3166-1 alpha-2 (case insensitive) country code of client request",
+        "default": "",
+        "pattern": "^[a-zA-Z]{2}$"
+      },
+      "subdivision": {
+        "type": "string",
+        "title": "Subdivision part of ISO 3166-2 (case insensitive) country-subdivision code of client request",
+        "default": "",
+        "pattern": "^[a-zA-Z0-9]{1,3}$"
+      }
+    },
+    "required": [
+      "country"
+    ]
+  }
+  ```
+
+A sample response for a user in Germany looks like:
+
+```
+{
+  "country": "de"
+}
+```
+
+A sample response for a user in California, US looks like:
+
+```
+{
+  "country": "us",
+  "subdivision": "ca"
+}
+```
+
+Note: As of April 2020, `us-ca` is the only subdivision supported by amp-geo.
+
+There are trade-offs in accuracy and performance when you set the client cache time for this API. Longer cache times are better for performance on subsequent page loads but can lead to incorrect country detection. For reference, `https://cdn.ampproject.org/v0/amp-geo-0.1.js` has a client cache time of 30 minutes.
+
+### HTTP response headers
+
+In addition to following [TLS best practices](https://infosec.mozilla.org/guidelines/web_security), consider the following headers when hosting the AMP framework:
+
+- `content-security-policy`: If your pages implement [AMP's CSP](https://amp.dev/documentation/guides-and-tutorials/optimize-and-measure/secure-pages/), apply a matching content security policy to your hosted framework responses. Inspect the headers on `https://cdn.ampproject.org/v0.js` for a base policy that should be expanded to include resources served from your host.
+- `access-control-allow-origin`: Some runtime components are fetched via XHR. If your AMP pages will be served from a different host than your framework, be sure to include CORS headers (see also [CORS Requests in AMP](https://github.com/ampproject/amphtml/blob/master/spec/amp-cors-requests.md)).
+- `content-type`: There are a few resources served without file extensions, or with extensions that may not be recognized by all web servers. In addition to [common types](https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/MIME_types/Common_types), you may want to include special handling for the following:
+
+  - `/rtv/metadata` - `application/json`
+  - `/amp_preconnect_polyfill_404_or_other_error_expected._Do_not_worry_about_it` - `text/html`
+
+  A complete list of files in each AMP release can be found in `files.txt`, for example `https://cdn.ampproject.org/files.txt`.
+
+- `cache-control`: The AMP framework hosted from versioned URLs should be "immutable"; users should expect to find the same content from these URLs for as long as the URLs are active (amp-geo is an exception, see below). Long cache times are appropriate. On the other hand, the AMP framework hosted from versionless URLs should be served with relatively short cache times so that minimal time is required for your latest update to reach all users.
+  - Versioned URL example: `cdn.ampproject.org` sets a 1 year client cache time on resources served under `cdn.ampproject.org/rtv/<rtv>`: `cache-control: public, max-age=31536000`.
+  - Versionless URL example: `cdn.ampproject.org` sets a 50 minute client cache time for resources served from versionless URLs, but also allows a long 2 week stale-while-revalidate time in the event that versionless URLs experience an outage: `cache-control: private, max-age=3000, stale-while-revalidate=1206600`.
+  - `amp-geo-*.(m)js`: If amp-geo hotpatching is utilized, there is a trade-off in accuracy and performance when you set this cache time. Longer cache times are better for performance on subsequent page loads but can lead to incorrect country detection. Both `cdn.ampproject.org/v0/amp-geo-0.1.js` and `cdn.ampproject.org/rtv/<rtv>/v0/amp-geo-0.1.js` set the client cache time to 30 minutes.
diff --git a/src/base-element.js b/src/base-element.js
index b9515b0b0af8..a250f0086726 100644
--- a/src/base-element.js
+++ b/src/base-element.js
@@ -429,6 +429,17 @@ export class BaseElement {
     return getMode(this.win).runtime == 'inabox' || 3;
   }
 
+  /**
+   * Allows for rendering outside of the constraint set by renderOutsideViewport
+   * so long task scheduler is idle.  Integer values less than those returned
+   * by renderOutsideViewport have no effect.  Subclasses can override (default
+   * is disabled).
+   * @return {boolean|number}
+   */
+  idleRenderOutsideViewport() {
+    return false;
+  }
+
   /**
    * Subclasses can override this method to opt-in into receiving additional
    * {@link layoutCallback} calls. Note that this method is not consulted for
diff --git a/src/custom-element.js b/src/custom-element.js
index 095b8810ed94..c5a86d01a783 100644
--- a/src/custom-element.js
+++ b/src/custom-element.js
@@ -1033,6 +1033,16 @@ function createBaseCustomElementClass(win) {
       return this.implementation_.renderOutsideViewport();
     }
 
+    /**
+     * Whether the element should render outside of renderOutsideViewport when
+     * the scheduler is idle.
+     * @return {boolean|number}
+     * @final
+     */
+    idleRenderOutsideViewport() {
+      return this.implementation_.idleRenderOutsideViewport();
+    }
+
     /**
      * Returns a previously measured layout box adjusted to the viewport. This
      * mainly affects fixed-position elements that are adjusted to be always
diff --git a/src/enums.js b/src/enums.js
new file mode 100644
index 000000000000..088974ec5a6c
--- /dev/null
+++ b/src/enums.js
@@ -0,0 +1,24 @@
+/**
+ * Copyright 2020 The AMP HTML Authors. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS-IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * Registred singleton on AMP doc.
+ * @enum {number}
+ */
+export const AMPDOC_SINGLETON_NAME = {
+  TRACKING_IFRAME: 1,
+  LINKER: 2,
+};
diff --git a/src/error.js b/src/error.js
index 4291403bacb9..f919ad70f917 100644
--- a/src/error.js
+++ b/src/error.js
@@ -640,7 +640,7 @@ export function getErrorReportData(
 
   // TODO(https://github.com/ampproject/error-tracker/issues/129): Remove once
   // all clients are serving a version with pre-throttling.
-  if (data['rt'] === 'production') {
+  if (data['bt'] === 'production') {
     // Setting this field allows the error reporting service to know that this
     // error has already been pre-throttled for Stable, so it doesn't need to
     // throttle again.
diff --git a/src/inabox/inabox-iframe-messaging-client.js b/src/inabox/inabox-iframe-messaging-client.js
index 6b96e47ab50e..f444249f3055 100644
--- a/src/inabox/inabox-iframe-messaging-client.js
+++ b/src/inabox/inabox-iframe-messaging-client.js
@@ -17,7 +17,6 @@
 import {IframeMessagingClient} from '../../3p/iframe-messaging-client';
 import {canInspectWindow} from '../iframe-helper';
 import {getExistingServiceOrNull, registerServiceBuilder} from '../service';
-import {isExperimentOn} from '../experiments';
 import {tryParseJson} from '../json';
 
 /**
@@ -35,10 +34,7 @@ export function iframeMessagingClientFor(win) {
  * @param {!Window} win
  */
 export function installIframeMessagingClient(win) {
-  if (
-    !isExperimentOn(win, 'inabox-viewport-friendly') ||
-    !canInspectWindow(win.top)
-  ) {
+  if (!canInspectWindow(win.top)) {
     registerServiceBuilder(
       win,
       'iframeMessagingClient',
diff --git a/src/inabox/inabox-viewport.js b/src/inabox/inabox-viewport.js
index 26c7f39b8c31..7fda5e07094e 100644
--- a/src/inabox/inabox-viewport.js
+++ b/src/inabox/inabox-viewport.js
@@ -24,7 +24,6 @@ import {dev, devAssert} from '../log';
 import {getFrameOverlayManager} from '../../ads/inabox/frame-overlay-manager.js';
 import {getPositionObserver} from '../../ads/inabox/position-observer';
 import {iframeMessagingClientFor} from './inabox-iframe-messaging-client';
-import {isExperimentOn} from '../experiments';
 import {isIframed} from '../dom';
 import {
   layoutRectFromDomRect,
@@ -481,9 +480,7 @@ export class ViewportBindingInabox {
     );
 
     /** @private @const {boolean} */
-    this.isFriendlyIframed_ =
-      isExperimentOn(this.win, 'inabox-viewport-friendly') &&
-      canInspectWindow(this.win.top);
+    this.isFriendlyIframed_ = canInspectWindow(this.win.top);
 
     /** @private {?../../ads/inabox/position-observer.PositionObserver} */
     this.topWindowPositionObserver_ = this.isFriendlyIframed_
diff --git a/src/multidoc-manager.js b/src/multidoc-manager.js
index 59019d82e781..f5713675dd78 100644
--- a/src/multidoc-manager.js
+++ b/src/multidoc-manager.js
@@ -28,6 +28,7 @@ import {disposeServicesForDoc, getServicePromiseOrNullForDoc} from './service';
 import {getMode} from './mode';
 import {installStylesForDoc} from './style-installer';
 import {isArray, isObject} from './types';
+import {parseExtensionUrl} from './service/extension-location';
 import {parseUrlDeprecated} from './url';
 import {setStyle} from './style';
 
@@ -417,15 +418,12 @@ export class MultidocManager {
             if (n.hasAttribute('src')) {
               dev().fine(TAG, '- src script: ', n);
               const src = n.getAttribute('src');
-              const isRuntime =
-                src.indexOf('/amp.js') != -1 || src.indexOf('/v0.js') != -1;
+              const urlParts = parseExtensionUrl(src);
+              const isRuntime = !urlParts.extensionId;
               // Note: Some extensions don't have [custom-element] or
               // [custom-template] e.g. amp-viewer-integration.
               const customElement = n.getAttribute('custom-element');
               const customTemplate = n.getAttribute('custom-template');
-              const versionRe = /-(\d+.\d+)(.max)?\.js$/;
-              const match = versionRe.exec(src);
-              const version = match ? match[1] : '0.1';
               if (isRuntime) {
                 dev().fine(TAG, '- ignore runtime script: ', src);
               } else if (customElement || customTemplate) {
@@ -433,14 +431,14 @@ export class MultidocManager {
                 this.extensions_.installExtensionForDoc(
                   ampdoc,
                   customElement || customTemplate,
-                  version
+                  urlParts.extensionVersion
                 );
                 dev().fine(
                   TAG,
                   '- load extension: ',
                   customElement || customTemplate,
                   ' ',
-                  version
+                  urlParts.extensionVersion
                 );
                 if (customElement) {
                   extensionIds.push(customElement);
diff --git a/src/preact/slot.js b/src/preact/slot.js
index 0eb5276241f2..4f88f3375c22 100644
--- a/src/preact/slot.js
+++ b/src/preact/slot.js
@@ -42,11 +42,10 @@ export function createSlot(element, name, props) {
  */
 export function Slot(props) {
   const context = useContext(getAmpContext());
-  const ref = useRef(null);
+  const ref = useRef(/** @type {?Element} */ (null));
   const slotProps = {...props, ref};
   useEffect(() => {
-    const {current} = dev().assertElement(ref);
-    const slot = dev().assertElement(current);
+    const slot = dev().assertElement(ref.current);
     const assignedElements = getAssignedElements(props, slot);
     slot.__assignedElements = assignedElements;
 
@@ -136,9 +135,9 @@ export function Slot(props) {
   // useEffect, because it must only be run once while the previous needs to
   // run every render.
   useMountEffect(() => {
+    const slot = dev().assertElement(ref.current);
+
     return () => {
-      const {current} = dev().assertElement(ref);
-      const slot = dev().assertElement(current);
       const affectedNodes = [];
       getAssignedElements(props, slot).forEach((node) => {
         affectedNodes.push.apply(affectedNodes, getAmpElements(node));
diff --git a/src/preact/utils.js b/src/preact/utils.js
index 3ec6a3c9e6f5..80a6334dee64 100644
--- a/src/preact/utils.js
+++ b/src/preact/utils.js
@@ -21,6 +21,7 @@ import {useContext, useEffect, useLayoutEffect} from './index';
  * @param {function()} callback
  */
 export function useMountEffect(callback) {
+  // eslint-disable-next-line react-hooks/exhaustive-deps
   useEffect(callback, [
     /* mount-only effect*/
   ]);
@@ -30,6 +31,7 @@ export function useMountEffect(callback) {
  * @param {function()} callback
  */
 export function useMountLayoutEffect(callback) {
+  // eslint-disable-next-line react-hooks/exhaustive-deps
   useLayoutEffect(callback, [
     /* mount-only effect*/
   ]);
diff --git a/src/purifier/package.json b/src/purifier/package.json
index eb0f8f7cc180..2d27709e2a81 100644
--- a/src/purifier/package.json
+++ b/src/purifier/package.json
@@ -20,7 +20,7 @@
   "homepage": "https://github.com/ampproject/amphtml/tree/master/src/purifier",
   "devDependencies": {
     "@rollup/plugin-alias": "3.1.0",
-    "rollup": "2.7.5"
+    "rollup": "2.9.1"
   },
   "dependencies": {
     "dompurify": "2.0.7"
diff --git a/src/service/ampdoc-impl.js b/src/service/ampdoc-impl.js
index f646da0afcb0..6ac07f97ad9f 100644
--- a/src/service/ampdoc-impl.js
+++ b/src/service/ampdoc-impl.js
@@ -308,8 +308,8 @@ export class AmpDoc {
     /** @public @const {!Window} */
     this.win = win;
 
-    /** @private */
-    this.hasTrackingIframe_ = false;
+    /** @private {!Object<../enums.AMPDOC_SINGLETON_NAME, boolean>} */
+    this.registeredSingleton_ = map();
 
     /** @public @const {?AmpDoc} */
     this.parent_ = parent;
@@ -754,16 +754,17 @@ export class AmpDoc {
   }
 
   /**
-   * Allow one tracking iframe for each amp doc. Caller need to handle user
-   * error when registeration returns false
+   * Attempt to register a singleton for each ampdoc.
+   * Caller need to handle user error when registration returns false.
+   * @param {!../enums.AMPDOC_SINGLETON_NAME} name
    * @return {boolean}
    */
-  registerTrackingIframe() {
-    if (this.hasTrackingIframe_) {
-      return false;
+  registerSingleton(name) {
+    if (!this.registeredSingleton_[name]) {
+      this.registeredSingleton_[name] = true;
+      return true;
     }
-    this.hasTrackingIframe_ = true;
-    return true;
+    return false;
   }
 }
 
diff --git a/src/service/extensions-impl.js b/src/service/extensions-impl.js
index 4b240d5771c6..12f1f26b9d49 100644
--- a/src/service/extensions-impl.js
+++ b/src/service/extensions-impl.js
@@ -243,11 +243,15 @@ export class Extensions {
    */
   reloadExtension(extensionId) {
     // Ignore inserted script elements to prevent recursion.
-    const el = this.getExtensionScript_(
+    const els = this.getExtensionScripts_(
       extensionId,
       /* includeInserted */ false
     );
-    devAssert(el, 'Cannot find script for extension: %s', extensionId);
+    devAssert(
+      els.length > 0,
+      'Cannot find script for extension: %s',
+      extensionId
+    );
     // The previously awaited extension loader must not have finished or
     // failed.
     const holder = this.extensions_[extensionId];
@@ -255,8 +259,10 @@ export class Extensions {
       devAssert(!holder.loaded && !holder.error);
       holder.scriptPresent = false;
     }
-    el.setAttribute('i-amphtml-loaded-new-version', extensionId);
-    const urlParts = parseExtensionUrl(el.src);
+    els.forEach((el) =>
+      el.setAttribute('i-amphtml-loaded-new-version', extensionId)
+    );
+    const urlParts = parseExtensionUrl(els[0].src);
     return this.preloadExtension(extensionId, urlParts.extensionVersion);
   }
 
@@ -266,10 +272,10 @@ export class Extensions {
    * @param {string} extensionId
    * @param {boolean=} includeInserted If true, includes script elements that
    *   are inserted by the runtime dynamically. Default is true.
-   * @return {?Element}
+   * @return {!Array<!Element>}
    * @private
    */
-  getExtensionScript_(extensionId, includeInserted = true) {
+  getExtensionScripts_(extensionId, includeInserted = true) {
     // Always ignore <script> elements that have a mismatched RTV.
     const modifier =
       ':not([i-amphtml-loaded-new-version])' +
@@ -279,14 +285,15 @@ export class Extensions {
     const matches = this.win.document.head./*OK*/ querySelectorAll(
       `script[src*="/${extensionId}-"]` + modifier
     );
+    const filtered = [];
     for (let i = 0; i < matches.length; i++) {
       const match = matches[i];
       const urlParts = parseExtensionUrl(match.src);
       if (urlParts.extensionId === extensionId) {
-        return match;
+        filtered.push(match);
       }
     }
-    return null;
+    return filtered;
   }
 
   /**
@@ -545,8 +552,8 @@ export class Extensions {
       return false;
     }
     if (holder.scriptPresent === undefined) {
-      const scriptInHead = this.getExtensionScript_(extensionId);
-      holder.scriptPresent = !!scriptInHead;
+      const scriptsInHead = this.getExtensionScripts_(extensionId);
+      holder.scriptPresent = scriptsInHead.length > 0;
     }
     return !holder.scriptPresent;
   }
diff --git a/src/service/localization.js b/src/service/localization.js
index 6ffb6c6727ac..48e153d90678 100644
--- a/src/service/localization.js
+++ b/src/service/localization.js
@@ -18,6 +18,7 @@
 // LocalizedStringId enum values and any other strings.
 // eslint-disable-next-line no-unused-vars
 import {LocalizedStringId} from '../localized-strings';
+import {Services} from '../services';
 import {closest} from '../dom';
 
 /**
@@ -92,12 +93,12 @@ export class LocalizationService {
    * @param {!Element} element
    */
   constructor(element) {
-    const rootEl = element.ownerDocument.documentElement;
+    this.element_ = element;
 
     /**
-     * @private @const {!Array<string>}
+     * @private @const {?string}
      */
-    this.rootLanguageCodes_ = this.getLanguageCodesForElement_(rootEl);
+    this.viewerLanguageCode_ = Services.viewerForDoc(element).getParam('lang');
 
     /**
      * A mapping of language code to localized string bundle.
@@ -114,7 +115,13 @@ export class LocalizationService {
   getLanguageCodesForElement_(element) {
     const languageEl = closest(element, (el) => el.hasAttribute('lang'));
     const languageCode = languageEl ? languageEl.getAttribute('lang') : null;
-    return getLanguageCodesFromString(languageCode || '');
+    const languageCodesToUse = getLanguageCodesFromString(languageCode || '');
+
+    if (this.viewerLanguageCode_) {
+      languageCodesToUse.unshift(this.viewerLanguageCode_);
+    }
+
+    return languageCodesToUse;
   }
 
   /**
@@ -145,10 +152,8 @@ export class LocalizationService {
    *     one exists, or the default otherwise.
    * @return {string|null}
    */
-  getLocalizedString(localizedStringId, elementToUse = undefined) {
-    const languageCodes = elementToUse
-      ? this.getLanguageCodesForElement_(elementToUse)
-      : this.rootLanguageCodes_;
+  getLocalizedString(localizedStringId, elementToUse = this.element_) {
+    const languageCodes = this.getLanguageCodesForElement_(elementToUse);
 
     return findLocalizedString(
       this.localizedStringBundles_,
diff --git a/src/service/resource.js b/src/service/resource.js
index 89254826c641..030268e1c3da 100644
--- a/src/service/resource.js
+++ b/src/service/resource.js
@@ -843,6 +843,15 @@ export class Resource {
     );
   }
 
+  /**
+   * Whether this is allowed to render when scheduler is idle but not in
+   * viewport.
+   * @return {boolean}
+   */
+  idleRenderOutsideViewport() {
+    return this.isWithinViewportRatio(this.element.idleRenderOutsideViewport());
+  }
+
   /**
    * Sets the resource's state to LAYOUT_SCHEDULED.
    * @param {number} scheduleTime The time at which layout was scheduled.
diff --git a/src/service/resources-impl.js b/src/service/resources-impl.js
index 869907535769..85ad154d5648 100644
--- a/src/service/resources-impl.js
+++ b/src/service/resources-impl.js
@@ -1349,8 +1349,27 @@ export class ResourcesImpl {
       this.queue_.getSize() == 0 &&
       now > this.exec_.getLastDequeueTime() + 5000
     ) {
+      // Phase 5: Idle Render Outside Viewport layout: layout up to 4 items
+      // with idleRenderOutsideViewport true
       let idleScheduledCount = 0;
-      // Phase 5: Idle layout: layout more if we are otherwise not doing much.
+      for (
+        let i = 0;
+        i < this.resources_.length && idleScheduledCount < 4;
+        i++
+      ) {
+        const r = this.resources_[i];
+        if (
+          r.getState() == ResourceState.READY_FOR_LAYOUT &&
+          !r.hasOwner() &&
+          r.isDisplayed() &&
+          r.idleRenderOutsideViewport()
+        ) {
+          dev().fine(TAG_, 'idleRenderOutsideViewport layout:', r.debugid);
+          this.scheduleLayoutOrPreload(r, /* layout */ false);
+          idleScheduledCount++;
+        }
+      }
+      // Phase 6: Idle layout: layout more if we are otherwise not doing much.
       // TODO(dvoytenko): document/estimate IDLE timeouts and other constants
       for (
         let i = 0;
@@ -1628,7 +1647,8 @@ export class ResourcesImpl {
     if (
       !forceOutsideViewport &&
       !resource.isInViewport() &&
-      !resource.renderOutsideViewport()
+      !resource.renderOutsideViewport() &&
+      !resource.idleRenderOutsideViewport()
     ) {
       return false;
     }
diff --git a/src/services.js b/src/services.js
index 370f76bcf38a..bc978685ac51 100644
--- a/src/services.js
+++ b/src/services.js
@@ -14,7 +14,6 @@
  * limitations under the License.
  */
 
-import {LocalizationService} from './service/localization';
 import {
   getAmpdoc,
   getExistingServiceForDocInEmbedScope,
@@ -22,7 +21,6 @@ import {
   getService,
   getServiceForDoc,
   getServicePromiseForDoc,
-  registerServiceBuilderForDoc,
 } from './service';
 import {
   getElementServiceForDoc,
@@ -546,22 +544,14 @@ export class Services {
   }
 
   /**
-   * @return {!./service/localization.LocalizationService}
    * @param {!Element} element
+   * @return {?./service/localization.LocalizationService}
    */
   static localizationForDoc(element) {
-    let service = /** @type {?./service/localization.LocalizationService} */ (getExistingServiceForDocInEmbedScope(
+    return /** @type {?./service/localization.LocalizationService} */ (getExistingServiceForDocInEmbedScope(
       element,
       'localization'
     ));
-
-    if (!service) {
-      service = new LocalizationService(element);
-      registerServiceBuilderForDoc(element, 'localization', function () {
-        return service;
-      });
-    }
-    return service;
   }
 
   /**
diff --git a/src/url.js b/src/url.js
index 3e027eee4501..9aeb2c301dd6 100644
--- a/src/url.js
+++ b/src/url.js
@@ -650,3 +650,15 @@ export function checkCorsUrl(url) {
 export function tryDecodeUriComponent(component, opt_fallback) {
   return tryDecodeUriComponent_(component, opt_fallback);
 }
+
+/**
+ * Adds the path to the given url.
+ *
+ * @param {!Location} url
+ * @param {string} path
+ * @return {string}
+ */
+export function appendPathToUrl(url, path) {
+  const pathname = url.pathname.replace(/\/?$/, '/') + path.replace(/^\//, '');
+  return url.origin + pathname + url.search + url.hash;
+}
diff --git a/test/integration/test-amphtml-ads.js b/test/integration/test-amphtml-ads.js
index 8ed0dbed8333..0fed096292b4 100644
--- a/test/integration/test-amphtml-ads.js
+++ b/test/integration/test-amphtml-ads.js
@@ -17,7 +17,6 @@
 import {RequestBank} from '../../testing/test-helper';
 import {maybeSwitchToCompiledJs} from '../../testing/iframe';
 import {parseQueryString} from '../../src/url';
-import {toggleExperiment} from '../../src/experiments';
 import {xhrServiceForTesting} from '../../src/service/xhr-impl';
 
 describe('AMPHTML ad on AMP Page', () => {
@@ -351,7 +350,6 @@ describe('A more real AMPHTML image ad', () => {
       });
 
       it('should properly render ad in a friendly iframe with viewability pings', () => {
-        toggleExperiment(env.win, 'inabox-viewport-friendly', true);
         writeFriendlyFrame(doc, iframe, adBody);
         return testVisibilityPings(0, 1000);
       });
diff --git a/test/manual/amp-analytics/performanceTestPages/visible-basic.html b/test/manual/amp-analytics/performance-test-pages/visible-basic.html
similarity index 100%
rename from test/manual/amp-analytics/performanceTestPages/visible-basic.html
rename to test/manual/amp-analytics/performance-test-pages/visible-basic.html
diff --git a/test/manual/amp-analytics/performanceTestPages/visible-multiple.html b/test/manual/amp-analytics/performance-test-pages/visible-multiple.html
similarity index 95%
rename from test/manual/amp-analytics/performanceTestPages/visible-multiple.html
rename to test/manual/amp-analytics/performance-test-pages/visible-multiple.html
index 995195d7383f..a6287dd2b9e1 100644
--- a/test/manual/amp-analytics/performanceTestPages/visible-multiple.html
+++ b/test/manual/amp-analytics/performance-test-pages/visible-multiple.html
@@ -1,12 +1,13 @@
 <!-- This testing page is meant to imitate a longer page with multiple sets of 
-text, images, links, and ads. -->
+text, images, links, and ads.
+TODO(micajuineho) add back ads when serving compiled js -->
 <!DOCTYPE html>
 <html lang="en" amp="" i-amphtml-layout="" transformed="self;v=1">
 
 <head>
     <script async="" src="https://cdn.ampproject.org/v0.js"></script>
     <script async="" custom-element="amp-analytics" src="https://cdn.ampproject.org/v0/amp-analytics-0.1.js"></script>
-    <script async="" custom-element="amp-ad" src="https://cdn.ampproject.org/v0/amp-ad-0.1.js"></script>
+    <!-- <script async="" custom-element="amp-ad" src="https://cdn.ampproject.org/v0/amp-ad-0.1.js"></script> -->
     <title>Test Article</title>
     <style amp-boilerplate="">
         body {
@@ -231,7 +232,7 @@
 
   <div>
       <amp-layout id="gtm-ad-141698" >
-          <amp-ad width="300" height="400" type="fake" id='i-amphtml-demo-id' data-vars-analytics-var="bar" src="/extensions/amp-ad-network-fake-impl/0.1/data/fake_amp.html">
+          <!-- <amp-ad width="300" height="400" type="fake" id='i-amphtml-demo-id' data-vars-analytics-var="bar" src="/extensions/amp-ad-network-fake-impl/0.1/data/fake_amp.html">
               <div placeholder></div>
               <div fallback></div>
           </amp-ad>
@@ -246,7 +247,7 @@
           <amp-ad width="300" height="400" type="fake" id='i-amphtml-demo-id' data-vars-analytics-var="bar" src="/extensions/amp-ad-network-fake-impl/0.1/data/fake_amp.html">
               <div placeholder></div>
               <div fallback></div>
-          </amp-ad>
+          </amp-ad> -->
       </amp-layout>
   </div>
   <div>
@@ -351,7 +352,7 @@ <h1>h1 header</h1>
       <div>
           <div>
               <amp-layout id="gtm-ad-141699">
-                  <amp-ad width="300" height="400" type="fake" id='i-amphtml-demo-id' data-vars-analytics-var="bar" src="/extensions/amp-ad-network-fake-impl/0.1/data/fake_amp.html">
+                  <!-- <amp-ad width="300" height="400" type="fake" id='i-amphtml-demo-id' data-vars-analytics-var="bar" src="/extensions/amp-ad-network-fake-impl/0.1/data/fake_amp.html">
                       <div placeholder></div>
                       <div fallback></div>
                   </amp-ad>
@@ -366,7 +367,7 @@ <h1>h1 header</h1>
                   <amp-ad width="300" height="400" type="fake" id='i-amphtml-demo-id' data-vars-analytics-var="bar" src="/extensions/amp-ad-network-fake-impl/0.1/data/fake_amp.html">
                       <div placeholder></div>
                       <div fallback></div>
-                  </amp-ad>
+                  </amp-ad> -->
               </amp-layout>
           </div>
       </div>
@@ -396,7 +397,7 @@ <h1>h1 header</h1>
           <div>
               <div>
                   <amp-layout id="gtm-ad-141701">
-                      <amp-ad width="300" height="400" type="fake" id='i-amphtml-demo-id' data-vars-analytics-var="bar" src="/extensions/amp-ad-network-fake-impl/0.1/data/fake_amp.html">
+                      <!-- <amp-ad width="300" height="400" type="fake" id='i-amphtml-demo-id' data-vars-analytics-var="bar" src="/extensions/amp-ad-network-fake-impl/0.1/data/fake_amp.html">
                           <div placeholder></div>
                           <div fallback></div>
                       </amp-ad>
@@ -411,7 +412,7 @@ <h1>h1 header</h1>
                       <amp-ad width="300" height="400" type="fake" id='i-amphtml-demo-id' data-vars-analytics-var="bar" src="/extensions/amp-ad-network-fake-impl/0.1/data/fake_amp.html">
                           <div placeholder></div>
                           <div fallback></div>
-                      </amp-ad>
+                      </amp-ad> -->
                   </amp-layout>
               </div>
           </div>
diff --git a/test/unit/inabox/test-inabox-viewport.js b/test/unit/inabox/test-inabox-viewport.js
index 8ddddbee2c4e..b51df78489fe 100644
--- a/test/unit/inabox/test-inabox-viewport.js
+++ b/test/unit/inabox/test-inabox-viewport.js
@@ -27,7 +27,6 @@ import {
 import {installIframeMessagingClient} from '../../../src/inabox/inabox-iframe-messaging-client';
 import {installPlatformService} from '../../../src/service/platform-impl';
 import {layoutRectLtwh} from '../../../src/layout-rect';
-import {toggleExperiment} from '../../../src/experiments';
 
 const NOOP = () => {};
 
@@ -92,12 +91,10 @@ describes.fakeWin('inabox-viewport', {amp: {}}, (env) => {
     };
     win.frameElement = iframeElement;
 
-    toggleExperiment(win, 'inabox-viewport-friendly', false);
     installIframeMessagingClient(win);
     installPlatformService(win);
     binding = new ViewportBindingInabox(win);
     env.sandbox./*OK*/ stub(iframeHelper, 'canInspectWindow').returns(true);
-    toggleExperiment(win, 'inabox-viewport-friendly', true);
     bindingFriendly = new ViewportBindingInabox(win);
     measureSpy = env.sandbox.spy();
     element = {
diff --git a/test/unit/test-extensions.js b/test/unit/test-extensions.js
index 3e7035e85a8b..e888b96a42ca 100644
--- a/test/unit/test-extensions.js
+++ b/test/unit/test-extensions.js
@@ -645,100 +645,279 @@ describes.sandboxed('Extensions', {}, () => {
       env.sandbox.stub(extensions, 'preloadExtension');
     });
 
-    it('should devAssert if script cannot be found', () => {
-      expect(() => {
-        allowConsoleError(() => extensions.reloadExtension('amp-list'));
-      }).to.throw('Cannot find script for extension: amp-list');
+    describe('regular scripts', () => {
+      it('should devAssert if script cannot be found', () => {
+        expect(() => {
+          allowConsoleError(() => extensions.reloadExtension('amp-list'));
+        }).to.throw('Cannot find script for extension: amp-list');
 
-      expect(extensions.preloadExtension).to.not.be.called;
-    });
+        expect(extensions.preloadExtension).to.not.be.called;
+      });
 
-    it('should ignore inserted scripts', () => {
-      const list = document.createElement('script');
-      list.setAttribute('custom-element', 'amp-list');
-      list.setAttribute('src', 'https://cdn.ampproject.org/v0/amp-list-0.1.js');
-      list.setAttribute('i-amphtml-inserted', '');
-      win.document.head.appendChild(list);
+      it('should ignore inserted scripts', () => {
+        const list = document.createElement('script');
+        list.setAttribute('custom-element', 'amp-list');
+        list.setAttribute(
+          'src',
+          'https://cdn.ampproject.org/v0/amp-list-0.1.js'
+        );
+        list.setAttribute('i-amphtml-inserted', '');
+        win.document.head.appendChild(list);
 
-      expect(() => {
-        allowConsoleError(() => extensions.reloadExtension('amp-list'));
-      }).to.throw('Cannot find script for extension: amp-list');
+        expect(() => {
+          allowConsoleError(() => extensions.reloadExtension('amp-list'));
+        }).to.throw('Cannot find script for extension: amp-list');
 
-      expect(list.hasAttribute('i-amphtml-loaded-new-version')).to.be.false;
-      expect(extensions.preloadExtension).to.not.be.called;
-    });
+        expect(list.hasAttribute('i-amphtml-loaded-new-version')).to.be.false;
+        expect(extensions.preloadExtension).to.not.be.called;
+      });
 
-    it('should support [custom-element] scripts', () => {
-      const list = document.createElement('script');
-      list.setAttribute('custom-element', 'amp-list');
-      list.setAttribute('src', 'https://cdn.ampproject.org/v0/amp-list-0.1.js');
-      win.document.head.appendChild(list);
+      it('should support [custom-element] scripts', () => {
+        const list = document.createElement('script');
+        list.setAttribute('custom-element', 'amp-list');
+        list.setAttribute(
+          'src',
+          'https://cdn.ampproject.org/v0/amp-list-0.1.js'
+        );
+        win.document.head.appendChild(list);
 
-      extensions.reloadExtension('amp-list');
+        extensions.reloadExtension('amp-list');
 
-      expect(list.getAttribute('i-amphtml-loaded-new-version')).to.equal(
-        'amp-list'
-      );
-      expect(extensions.preloadExtension).to.be.calledWith('amp-list', '0.1');
-    });
+        expect(list.getAttribute('i-amphtml-loaded-new-version')).to.equal(
+          'amp-list'
+        );
+        expect(extensions.preloadExtension).to.be.calledWith('amp-list', '0.1');
+      });
 
-    it('should support "latest" version scripts', () => {
-      const list = document.createElement('script');
-      list.setAttribute('custom-element', 'amp-list');
-      list.setAttribute(
-        'src',
-        'https://cdn.ampproject.org/v0/amp-list-latest.js'
-      );
-      win.document.head.appendChild(list);
+      it('should support "latest" version scripts', () => {
+        const list = document.createElement('script');
+        list.setAttribute('custom-element', 'amp-list');
+        list.setAttribute(
+          'src',
+          'https://cdn.ampproject.org/v0/amp-list-latest.js'
+        );
+        win.document.head.appendChild(list);
 
-      extensions.reloadExtension('amp-list');
+        extensions.reloadExtension('amp-list');
 
-      expect(list.getAttribute('i-amphtml-loaded-new-version')).to.equal(
-        'amp-list'
-      );
-      expect(extensions.preloadExtension).to.be.calledWith(
-        'amp-list',
-        'latest'
-      );
-    });
+        expect(list.getAttribute('i-amphtml-loaded-new-version')).to.equal(
+          'amp-list'
+        );
+        expect(extensions.preloadExtension).to.be.calledWith(
+          'amp-list',
+          'latest'
+        );
+      });
 
-    it('should support [custom-template] scripts', () => {
-      const mustache = document.createElement('script');
-      mustache.setAttribute('custom-template', 'amp-mustache');
-      mustache.setAttribute(
-        'src',
-        'https://cdn.ampproject.org/v0/amp-mustache-0.2.js'
-      );
-      win.document.head.appendChild(mustache);
+      it('should support [custom-template] scripts', () => {
+        const mustache = document.createElement('script');
+        mustache.setAttribute('custom-template', 'amp-mustache');
+        mustache.setAttribute(
+          'src',
+          'https://cdn.ampproject.org/v0/amp-mustache-0.2.js'
+        );
+        win.document.head.appendChild(mustache);
 
-      extensions.reloadExtension('amp-mustache');
+        extensions.reloadExtension('amp-mustache');
 
-      expect(mustache.getAttribute('i-amphtml-loaded-new-version')).to.equal(
-        'amp-mustache'
-      );
-      expect(extensions.preloadExtension).to.be.calledWith(
-        'amp-mustache',
-        '0.2'
-      );
+        expect(mustache.getAttribute('i-amphtml-loaded-new-version')).to.equal(
+          'amp-mustache'
+        );
+        expect(extensions.preloadExtension).to.be.calledWith(
+          'amp-mustache',
+          '0.2'
+        );
+      });
+
+      it('should support no-attribute scripts', () => {
+        const viewer = document.createElement('script');
+        viewer.setAttribute(
+          'src',
+          'https://cdn.ampproject.org/v0/amp-viewer-integration-0.1.js'
+        );
+        win.document.head.appendChild(viewer);
+
+        extensions.reloadExtension('amp-viewer-integration');
+
+        expect(viewer.getAttribute('i-amphtml-loaded-new-version')).to.equal(
+          'amp-viewer-integration'
+        );
+        expect(extensions.preloadExtension).to.be.calledWith(
+          'amp-viewer-integration',
+          '0.1'
+        );
+      });
     });
 
-    it('should support no-attribute scripts', () => {
-      const viewer = document.createElement('script');
-      viewer.setAttribute(
-        'src',
-        'https://cdn.ampproject.org/v0/amp-viewer-integration-0.1.js'
-      );
-      win.document.head.appendChild(viewer);
+    describe('module/nomdule script pairs', () => {
+      it('should devAssert if script cannot be found', () => {
+        expect(() => {
+          allowConsoleError(() => extensions.reloadExtension('amp-list'));
+        }).to.throw('Cannot find script for extension: amp-list');
 
-      extensions.reloadExtension('amp-viewer-integration');
+        expect(extensions.preloadExtension).to.not.be.called;
+      });
 
-      expect(viewer.getAttribute('i-amphtml-loaded-new-version')).to.equal(
-        'amp-viewer-integration'
-      );
-      expect(extensions.preloadExtension).to.be.calledWith(
-        'amp-viewer-integration',
-        '0.1'
-      );
+      it('should ignore inserted scripts', () => {
+        const mod = document.createElement('script');
+        mod.setAttribute('custom-element', 'amp-list');
+        mod.setAttribute(
+          'src',
+          'https://cdn.ampproject.org/v0/amp-list-0.1.mjs'
+        );
+        mod.setAttribute('i-amphtml-inserted', '');
+        mod.setAttribute('type', 'module');
+        win.document.head.appendChild(mod);
+
+        const nomod = document.createElement('script');
+        nomod.setAttribute('custom-element', 'amp-list');
+        nomod.setAttribute(
+          'src',
+          'https://cdn.ampproject.org/v0/amp-list-0.1.js'
+        );
+        nomod.setAttribute('i-amphtml-inserted', '');
+        nomod.setAttribute('nomodule', '');
+        win.document.head.appendChild(nomod);
+
+        expect(() => {
+          allowConsoleError(() => extensions.reloadExtension('amp-list'));
+        }).to.throw('Cannot find script for extension: amp-list');
+
+        expect(mod.hasAttribute('i-amphtml-loaded-new-version')).to.be.false;
+        expect(nomod.hasAttribute('i-amphtml-loaded-new-version')).to.be.false;
+        expect(extensions.preloadExtension).to.not.be.called;
+      });
+
+      it('should support [custom-element] scripts', () => {
+        const mod = document.createElement('script');
+        mod.setAttribute('custom-element', 'amp-list');
+        mod.setAttribute(
+          'src',
+          'https://cdn.ampproject.org/v0/amp-list-0.1.mjs'
+        );
+        mod.setAttribute('type', 'module');
+        win.document.head.appendChild(mod);
+
+        const nomod = document.createElement('script');
+        nomod.setAttribute('custom-element', 'amp-list');
+        nomod.setAttribute(
+          'src',
+          'https://cdn.ampproject.org/v0/amp-list-0.1.js'
+        );
+        nomod.setAttribute('nomodule', '');
+        win.document.head.appendChild(nomod);
+
+        extensions.reloadExtension('amp-list');
+
+        expect(mod.getAttribute('i-amphtml-loaded-new-version')).to.equal(
+          'amp-list'
+        );
+        expect(nomod.getAttribute('i-amphtml-loaded-new-version')).to.equal(
+          'amp-list'
+        );
+        expect(extensions.preloadExtension).to.be.calledOnce;
+        expect(extensions.preloadExtension).to.be.calledWith('amp-list', '0.1');
+      });
+
+      it('should support "latest" version scripts', () => {
+        const mod = document.createElement('script');
+        mod.setAttribute('custom-element', 'amp-list');
+        mod.setAttribute(
+          'src',
+          'https://cdn.ampproject.org/v0/amp-list-latest.mjs'
+        );
+        mod.setAttribute('type', 'module');
+        win.document.head.appendChild(mod);
+
+        const nomod = document.createElement('script');
+        nomod.setAttribute('custom-element', 'amp-list');
+        nomod.setAttribute(
+          'src',
+          'https://cdn.ampproject.org/v0/amp-list-latest.js'
+        );
+        nomod.setAttribute('nomodule', '');
+        win.document.head.appendChild(nomod);
+
+        extensions.reloadExtension('amp-list');
+
+        expect(mod.getAttribute('i-amphtml-loaded-new-version')).to.equal(
+          'amp-list'
+        );
+        expect(nomod.getAttribute('i-amphtml-loaded-new-version')).to.equal(
+          'amp-list'
+        );
+        expect(extensions.preloadExtension).to.be.calledOnce;
+        expect(extensions.preloadExtension).to.be.calledWith(
+          'amp-list',
+          'latest'
+        );
+      });
+
+      it('should support [custom-template] scripts', () => {
+        const mod = document.createElement('script');
+        mod.setAttribute('custom-template', 'amp-mustache');
+        mod.setAttribute(
+          'src',
+          'https://cdn.ampproject.org/v0/amp-mustache-0.2.mjs'
+        );
+        mod.setAttribute('type', 'module');
+        win.document.head.appendChild(mod);
+
+        const nomod = document.createElement('script');
+        nomod.setAttribute('custom-template', 'amp-mustache');
+        nomod.setAttribute(
+          'src',
+          'https://cdn.ampproject.org/v0/amp-mustache-0.2.js'
+        );
+        nomod.setAttribute('nomodule', '');
+        win.document.head.appendChild(nomod);
+
+        extensions.reloadExtension('amp-mustache');
+
+        expect(mod.getAttribute('i-amphtml-loaded-new-version')).to.equal(
+          'amp-mustache'
+        );
+        expect(nomod.getAttribute('i-amphtml-loaded-new-version')).to.equal(
+          'amp-mustache'
+        );
+        expect(extensions.preloadExtension).to.be.calledOnce;
+        expect(extensions.preloadExtension).to.be.calledWith(
+          'amp-mustache',
+          '0.2'
+        );
+      });
+
+      it('should support no-attribute scripts', () => {
+        const mod = document.createElement('script');
+        mod.setAttribute(
+          'src',
+          'https://cdn.ampproject.org/v0/amp-viewer-integration-0.1.mjs'
+        );
+        mod.setAttribute('type', 'module');
+        win.document.head.appendChild(mod);
+
+        const nomod = document.createElement('script');
+        nomod.setAttribute(
+          'src',
+          'https://cdn.ampproject.org/v0/amp-viewer-integration-0.1.js'
+        );
+        nomod.setAttribute('nomodule', '');
+        win.document.head.appendChild(nomod);
+
+        extensions.reloadExtension('amp-viewer-integration');
+
+        expect(mod.getAttribute('i-amphtml-loaded-new-version')).to.equal(
+          'amp-viewer-integration'
+        );
+        expect(nomod.getAttribute('i-amphtml-loaded-new-version')).to.equal(
+          'amp-viewer-integration'
+        );
+        expect(extensions.preloadExtension).to.be.calledOnce;
+        expect(extensions.preloadExtension).to.be.calledWith(
+          'amp-viewer-integration',
+          '0.1'
+        );
+      });
     });
   });
 
diff --git a/test/unit/test-localization.js b/test/unit/test-localization.js
index 79dd85b8501c..a4d7dedeecc7 100644
--- a/test/unit/test-localization.js
+++ b/test/unit/test-localization.js
@@ -14,12 +14,15 @@
  * limitations under the License.
  */
 
+import {
+  LocalizationService,
+  getLanguageCodesFromString,
+} from '../../src/service/localization';
 import {
   LocalizedStringId,
   createPseudoLocale,
 } from '../../src/localized-strings';
 import {Services} from '../../src/services';
-import {getLanguageCodesFromString} from '../../src/service/localization';
 
 describes.fakeWin('localization', {amp: true}, (env) => {
   let win;
@@ -65,9 +68,7 @@ describes.fakeWin('localization', {amp: true}, (env) => {
 
   describe('localization service', () => {
     it('should get string text', () => {
-      const localizationService = Services.localizationForDoc(
-        win.document.body
-      );
+      const localizationService = new LocalizationService(win.document.body);
       localizationService.registerLocalizedStringBundle('en', {
         'test_string_id': {
           string: 'test string content',
@@ -81,9 +82,7 @@ describes.fakeWin('localization', {amp: true}, (env) => {
 
     it('should handle registration of uppercase locales', () => {
       env.win.document.documentElement.setAttribute('lang', 'zh-CN');
-      const localizationService = Services.localizationForDoc(
-        win.document.body
-      );
+      const localizationService = new LocalizationService(win.document.body);
       localizationService.registerLocalizedStringBundle('zh-CN', {
         '123': {
           string: '买票',
@@ -94,9 +93,7 @@ describes.fakeWin('localization', {amp: true}, (env) => {
     });
 
     it('should utilize fallback if string is missing', () => {
-      const localizationService = Services.localizationForDoc(
-        win.document.body
-      );
+      const localizationService = new LocalizationService(win.document.body);
       localizationService.registerLocalizedStringBundle('en', {
         'test_string_id': {
           fallback: 'test fallback content',
@@ -109,9 +106,7 @@ describes.fakeWin('localization', {amp: true}, (env) => {
     });
 
     it('should not utilize fallback if string is present', () => {
-      const localizationService = Services.localizationForDoc(
-        win.document.body
-      );
+      const localizationService = new LocalizationService(win.document.body);
       localizationService.registerLocalizedStringBundle('en', {
         'test_string_id': {
           string: 'test string content',
@@ -170,3 +165,65 @@ describes.fakeWin('localization', {amp: true}, (env) => {
     });
   });
 });
+
+describes.fakeWin('viewer localization', {amp: true}, (env) => {
+  describe('viewer language override', () => {
+    let win;
+
+    beforeEach(() => {
+      win = env.win;
+      env.sandbox
+        .stub(Services.viewerForDoc(env.ampdoc), 'getParam')
+        .returns('fr');
+    });
+
+    it('should take precedence over document language', () => {
+      const localizationService = new LocalizationService(win.document.body);
+      localizationService.registerLocalizedStringBundle('fr', {
+        'test_string_id': {
+          string: 'oui',
+        },
+      });
+      localizationService.registerLocalizedStringBundle('en', {
+        'test_string_id': {
+          string: 'yes',
+        },
+      });
+
+      expect(localizationService.getLocalizedString('test_string_id')).to.equal(
+        'oui'
+      );
+    });
+
+    it('should fall back if string is not found', () => {
+      const localizationService = new LocalizationService(win.document.body);
+      localizationService.registerLocalizedStringBundle('fr', {
+        'incorrect_test_string_id': {
+          string: 'non',
+        },
+      });
+      localizationService.registerLocalizedStringBundle('en', {
+        'correct_test_string_id': {
+          string: 'yes',
+        },
+      });
+
+      expect(
+        localizationService.getLocalizedString('correct_test_string_id')
+      ).to.equal('yes');
+    });
+
+    it('should fall back if language code is not registered', () => {
+      const localizationService = new LocalizationService(win.document.body);
+      localizationService.registerLocalizedStringBundle('en', {
+        'test_string_id': {
+          string: 'yes',
+        },
+      });
+
+      expect(localizationService.getLocalizedString('test_string_id')).to.equal(
+        'yes'
+      );
+    });
+  });
+});
diff --git a/test/unit/test-resource.js b/test/unit/test-resource.js
index 8f91cd297395..0a75d2738843 100644
--- a/test/unit/test-resource.js
+++ b/test/unit/test-resource.js
@@ -1010,6 +1010,59 @@ describes.realWin('Resource', {amp: true}, (env) => {
   });
 });
 
+describe('Resource idleRenderOutsideViewport', () => {
+  let element;
+  let resources;
+  let resource;
+  let idleRenderOutsideViewport;
+  let isWithinViewportRatio;
+
+  beforeEach(() => {
+    idleRenderOutsideViewport = window.sandbox.stub();
+    element = {
+      idleRenderOutsideViewport,
+      ownerDocument: {defaultView: window},
+      tagName: 'AMP-AD',
+      hasAttribute: () => false,
+      isBuilt: () => false,
+      isBuilding: () => false,
+      isUpgraded: () => false,
+      prerenderAllowed: () => false,
+      renderOutsideViewport: () => true,
+      build: () => false,
+      getBoundingClientRect: () => null,
+      updateLayoutBox: () => {},
+      isRelayoutNeeded: () => false,
+      layoutCallback: () => {},
+      applySize: () => {},
+      unlayoutOnPause: () => false,
+      unlayoutCallback: () => true,
+      pauseCallback: () => false,
+      resumeCallback: () => false,
+      viewportCallback: () => {},
+      getLayoutPriority: () => LayoutPriority.CONTENT,
+    };
+    resources = new ResourcesImpl(new AmpDocSingle(window));
+    resource = new Resource(1, element, resources);
+    isWithinViewportRatio = window.sandbox.stub(
+      resource,
+      'isWithinViewportRatio'
+    );
+  });
+
+  it('should return true if isWithinViewportRatio', () => {
+    idleRenderOutsideViewport.returns(5);
+    isWithinViewportRatio.withArgs(5).returns(true);
+    expect(resource.idleRenderOutsideViewport()).to.equal(true);
+  });
+
+  it('should return false for false element idleRenderOutsideViewport', () => {
+    idleRenderOutsideViewport.returns(false);
+    isWithinViewportRatio.withArgs(false).returns(false);
+    expect(resource.idleRenderOutsideViewport()).to.equal(false);
+  });
+});
+
 describes.realWin('Resource renderOutsideViewport', {amp: true}, (env) => {
   let element;
   let resources;
diff --git a/test/unit/test-resources.js b/test/unit/test-resources.js
index f340bb65b294..3e66c5b8b228 100644
--- a/test/unit/test-resources.js
+++ b/test/unit/test-resources.js
@@ -336,6 +336,7 @@ describe('Resources', () => {
         isInViewport: () => false,
         prerenderAllowed: () => true,
         renderOutsideViewport: () => false,
+        idleRenderOutsideViewport: () => false,
         startLayout: () => {},
         applySizesAndMediaQuery: () => {},
       };
@@ -355,6 +356,7 @@ describe('Resources', () => {
         isInViewport: () => false,
         prerenderAllowed: () => true,
         renderOutsideViewport: () => false,
+        idleRenderOutsideViewport: () => false,
         getLayoutPriority: () => LayoutPriority.METADATA,
         startLayout: () => {},
         layoutScheduled: () => {},
@@ -383,6 +385,31 @@ describe('Resources', () => {
         isInViewport: () => false,
         prerenderAllowed: () => true,
         renderOutsideViewport: () => true,
+        idleRenderOutsideViewport: () => false,
+        getLayoutPriority: () => LayoutPriority.METADATA,
+        startLayout: () => {},
+        layoutScheduled: () => {},
+        getTaskId: () => 'resource#L',
+        applySizesAndMediaQuery: () => {},
+      };
+      resources.scheduleLayoutOrPreload(resource, true);
+      expect(resources.queue_.getSize()).to.equal(1);
+      expect(resources.queue_.tasks_[0].forceOutsideViewport).to.be.false;
+    }
+  );
+
+  it(
+    'should schedule idleRenderOutsideViewport resource when' +
+      ' resource is not visible',
+    () => {
+      const resource = {
+        getState: () => ResourceState.READY_FOR_LAYOUT,
+        isDisplayed: () => true,
+        isFixed: () => false,
+        isInViewport: () => false,
+        prerenderAllowed: () => true,
+        renderOutsideViewport: () => false,
+        idleRenderOutsideViewport: () => true,
         getLayoutPriority: () => LayoutPriority.METADATA,
         startLayout: () => {},
         layoutScheduled: () => {},
@@ -585,6 +612,8 @@ describes.realWin('Resources discoverWork', {amp: true}, (env) => {
     element.getLayoutPriority = () => LayoutPriority.CONTENT;
     element.dispatchCustomEvent = () => {};
     element.getLayout = () => 'fixed';
+
+    element.idleRenderOutsideViewport = () => true;
     element.isInViewport = () => false;
     element.getAttribute = () => null;
     element.hasAttribute = () => false;
@@ -973,6 +1002,7 @@ describes.realWin('Resources discoverWork', {amp: true}, (env) => {
     const layoutCanceledSpy = sandbox.spy(resource1, 'layoutCanceled');
     sandbox.stub(resource1, 'isInViewport').returns(false);
     sandbox.stub(resource1, 'renderOutsideViewport').returns(false);
+    sandbox.stub(resource1, 'idleRenderOutsideViewport').returns(false);
     resources.work_();
     expect(resources.exec_.getSize()).to.equal(0);
     expect(measureSpy).to.be.calledOnce;
@@ -993,6 +1023,7 @@ describes.realWin('Resources discoverWork', {amp: true}, (env) => {
     const measureSpy = sandbox.spy(resource1, 'measure');
     sandbox.stub(resource1, 'isInViewport').returns(false);
     sandbox.stub(resource1, 'renderOutsideViewport').returns(false);
+    sandbox.stub(resource1, 'idleRenderOutsideViewport').returns(false);
     resources.work_();
     expect(resources.exec_.getSize()).to.equal(1);
     expect(measureSpy).to.be.calledOnce;
@@ -1083,6 +1114,7 @@ describes.realWin('Resources discoverWork', {amp: true}, (env) => {
       .returns(true)
       .onSecondCall()
       .returns(false);
+    resource2.element.idleRenderOutsideViewport = () => false;
     resource1.state_ = ResourceState.NOT_BUILT;
     resource1.build = sandbox.spy();
 
@@ -1106,6 +1138,7 @@ describes.realWin('Resources discoverWork', {amp: true}, (env) => {
       .returns(false)
       .onSecondCall()
       .returns(true);
+    resource2.element.idleRenderOutsideViewport = () => false;
     resource1.state_ = ResourceState.NOT_BUILT;
     resource1.build = sandbox.spy();
 
@@ -1126,6 +1159,7 @@ describes.realWin('Resources discoverWork', {amp: true}, (env) => {
     resource1.prerenderAllowed = () => false;
     resource1.state_ = ResourceState.NOT_BUILT;
     resource1.build = sandbox.spy();
+    resource2.element.idleRenderOutsideViewport = () => false;
 
     resources.discoverWork_();
 
@@ -1139,6 +1173,7 @@ describes.realWin('Resources discoverWork', {amp: true}, (env) => {
     resources.buildAttemptsCount_ = 21; // quota is 20
 
     resource1.element.isBuilt = () => false;
+    resource1.element.idleRenderOutsideViewport = () => true;
     resource1.prerenderAllowed = () => true;
     resource1.isBuildRenderBlocking = () => false;
     resource1.state_ = ResourceState.NOT_BUILT;
@@ -1155,6 +1190,7 @@ describes.realWin('Resources discoverWork', {amp: true}, (env) => {
     resources.buildAttemptsCount_ = 21; // quota is 20
 
     resource1.element.isBuilt = () => false;
+    resource1.element.idleRenderOutsideViewport = () => true;
     resource1.prerenderAllowed = () => true;
     resource1.isBuildRenderBlocking = () => true;
     resource1.state_ = ResourceState.NOT_BUILT;
@@ -1164,12 +1200,29 @@ describes.realWin('Resources discoverWork', {amp: true}, (env) => {
     expect(resource1.build).to.be.called;
   });
 
+  it('should layout resource if outside viewport but idle', () => {
+    const schedulePassStub = sandbox.stub(resources, 'schedulePass');
+    resources.documentReady_ = true;
+    sandbox.stub(resource1.element, 'nextSibling').returns({});
+    resource1.element.isBuilt = () => true;
+    resource1.element.renderOutsideViewport = () => false;
+    resource1.element.idleRenderOutsideViewport = () => true;
+    resource2.element.renderOutsideViewport = () => false;
+    resource2.element.idleRenderOutsideViewport = () => false;
+    resource1.state_ = ResourceState.READY_FOR_LAYOUT;
+
+    resources.discoverWork_();
+
+    expect(schedulePassStub).to.be.calledOnce;
+  });
+
   it('should force build resources during discoverWork layout phase', () => {
     const buildResourceSpy = sandbox.spy(resources, 'buildResourceUnsafe_');
     sandbox.stub(resources, 'schedule_');
     resources.documentReady_ = true;
     // Emulates a resource not building.
     resource1.element.isBuilt = sandbox.stub().returns(false);
+    resource2.element.idleRenderOutsideViewport = () => false;
     resource1.state_ = ResourceState.NOT_BUILT;
     resource1.build = sandbox.spy();
 
diff --git a/test/unit/test-runtime.js b/test/unit/test-runtime.js
index 420d7aa9ca4b..630a24a9d141 100644
--- a/test/unit/test-runtime.js
+++ b/test/unit/test-runtime.js
@@ -542,7 +542,7 @@ describes.fakeWin(
         const s = document.createElement('script');
         const name = 'amp-test-element' + index;
         s.setAttribute('custom-element', name);
-        s.setAttribute('src', `/${name}-0.1.js`);
+        s.setAttribute('src', `https://cdn.ampproject.org/v0/${name}-0.1.js`);
         win.document.head.appendChild(s);
         return s;
       }
@@ -1086,7 +1086,10 @@ describes.realWin(
 
         const script = win.document.createElement('script');
         script.setAttribute('custom-element', 'amp-ext');
-        script.setAttribute('src', '');
+        script.setAttribute(
+          'src',
+          'https://cdn.ampproject.org/v0/amp-ext-0.1.js'
+        );
         importDoc.head.appendChild(script);
 
         win.AMP.attachShadowDoc(hostElement, importDoc, docUrl);
@@ -1218,7 +1221,7 @@ describes.realWin(
         ).to.contain('.keyframes');
       });
 
-      it('should ignore runtime extension', () => {
+      it('should ignore runtime', () => {
         extensionsMock.expects('preloadExtension').never();
 
         const scriptEl = win.document.createElement('script');
@@ -1227,6 +1230,15 @@ describes.realWin(
         win.AMP.attachShadowDoc(hostElement, importDoc, docUrl);
       });
 
+      it('should ignore mjs runtime', () => {
+        extensionsMock.expects('preloadExtension').never();
+
+        const scriptEl = win.document.createElement('script');
+        scriptEl.setAttribute('src', 'https://cdn.ampproject.org/v0.mjs');
+        importDoc.head.appendChild(scriptEl);
+        win.AMP.attachShadowDoc(hostElement, importDoc, docUrl);
+      });
+
       it('should ignore unknown script', () => {
         extensionsMock.expects('preloadExtension').never();
 
@@ -1259,13 +1271,51 @@ describes.realWin(
 
         const scriptEl = win.document.createElement('script');
         scriptEl.setAttribute('custom-element', 'amp-ext1');
-        scriptEl.setAttribute('src', '');
+        scriptEl.setAttribute(
+          'src',
+          'https://cdn.ampproject.org/v0/amp-ext-0.1.js'
+        );
         importDoc.head.appendChild(scriptEl);
         win.AMP.attachShadowDoc(hostElement, importDoc, docUrl);
         expect(win.document.querySelector('script[custom-element="amp-ext1"]'))
           .to.not.exist;
       });
 
+      it('should import module/nomodule extension element', () => {
+        extensionsMock
+          .expects('preloadExtension')
+          .withExactArgs('amp-ext1', '0.1')
+          .returns(
+            Promise.resolve({
+              elements: {
+                'amp-ext1': function () {},
+              },
+            })
+          )
+          .once();
+
+        const mod = win.document.createElement('script');
+        mod.setAttribute('custom-element', 'amp-ext1');
+        mod.setAttribute(
+          'src',
+          'https://cdn.ampproject.org/v0/amp-ext-0.1.mjs'
+        );
+        mod.setAttribute('type', 'module');
+        const nomod = win.document.createElement('script');
+        nomod.setAttribute('custom-element', 'amp-ext1');
+        nomod.setAttribute(
+          'src',
+          'https://cdn.ampproject.org/v0/amp-ext-0.1.js'
+        );
+        nomod.setAttribute('nomodule', '');
+
+        importDoc.head.appendChild(mod);
+        importDoc.head.appendChild(nomod);
+        win.AMP.attachShadowDoc(hostElement, importDoc, docUrl);
+        expect(win.document.querySelector('script[custom-element="amp-ext1"]'))
+          .to.not.exist;
+      });
+
       it('should import extension element with version ≠ 0.1', () => {
         extensionsMock
           .expects('preloadExtension')
@@ -1300,7 +1350,10 @@ describes.realWin(
 
         const scriptEl = win.document.createElement('script');
         scriptEl.setAttribute('custom-template', 'amp-ext1');
-        scriptEl.setAttribute('src', '');
+        scriptEl.setAttribute(
+          'src',
+          'https://cdn.ampproject.org/v0/amp-ext1-0.1.js'
+        );
         importDoc.head.appendChild(scriptEl);
         win.AMP.attachShadowDoc(hostElement, importDoc, docUrl);
         expect(win.document.querySelector('script[custom-template="amp-ext1"]'))
@@ -1456,7 +1509,9 @@ describes.realWin(
             },
           });
 
-          writer.write('<script custom-element="amp-ext" src=""></script>');
+          writer.write(
+            '<script custom-element="amp-ext" src="https://cdn.ampproject.org/v0/amp-ext-0.1.js"></script>'
+          );
           writer.write('<body>');
 
           return ampdoc.waitForBodyOpen().then(() => {
@@ -1627,11 +1682,6 @@ describes.realWin(
         });
 
         it('should ignore unknown script', () => {
-          expectAsyncConsoleError(
-            '[multidoc-manager] - unknown script:  [object HTMLScriptElement] ' +
-              'https://cdn.ampproject.org/other.js'
-          );
-
           shadowDoc = win.AMP.attachShadowDocAsStream(hostElement, docUrl);
           writer = shadowDoc.writer;
           extensionsMock.expects('preloadExtension').never();
@@ -1665,7 +1715,9 @@ describes.realWin(
               })
             )
             .once();
-          writer.write('<script custom-element="amp-ext1" src=""></script>');
+          writer.write(
+            '<script custom-element="amp-ext1" src="https://cdn.ampproject.org/v0/amp-ext1-0.1.js"></script>'
+          );
           writer.write('<body>');
           return ampdoc.waitForBodyOpen().then(() => {
             expect(
@@ -1682,7 +1734,9 @@ describes.realWin(
             .withExactArgs('amp-ext1', '0.1')
             .returns(Promise.resolve({elements: {}}))
             .once();
-          writer.write('<script custom-template="amp-ext1" src=""></script>');
+          writer.write(
+            '<script custom-template="amp-ext1" src="https://cdn.ampproject.org/v0/amp-ext1-0.1.js"></script>'
+          );
           writer.write('<body>');
           return ampdoc.waitForBodyOpen().then(() => {
             expect(
diff --git a/test/unit/test-url.js b/test/unit/test-url.js
index 563698fb6f31..7840b10b81f5 100644
--- a/test/unit/test-url.js
+++ b/test/unit/test-url.js
@@ -14,10 +14,12 @@
  * limitations under the License.
  */
 
+import {Services} from '../../src/services';
 import {
   addMissingParamsToUrl,
   addParamToUrl,
   addParamsToUrl,
+  appendPathToUrl,
   assertAbsoluteHttpOrHttpsUrl,
   assertHttpsUrl,
   getCorsUrl,
@@ -1109,3 +1111,58 @@ describe('getProxyServingType', () => {
     ).to.equal('test');
   });
 });
+
+describes.realWin('appendPathToUrl', {'amp': true}, (env) => {
+  let urlService;
+  beforeEach(() => {
+    urlService = Services.urlForDoc(env.win.document.body);
+  });
+
+  it('should properly join url and path', () => {
+    expect(
+      appendPathToUrl(urlService.parse('https://cdn.ampproject.org'), '/foo')
+    ).to.be.equal('https://cdn.ampproject.org/foo');
+  });
+
+  it('should join url and path if none contain /', () => {
+    expect(
+      appendPathToUrl(urlService.parse('https://cdn.ampproject.org'), 'foo')
+    ).to.be.equal('https://cdn.ampproject.org/foo');
+  });
+
+  it('should properly join url with path, and path', () => {
+    expect(
+      appendPathToUrl(
+        urlService.parse('https://cdn.ampproject.org/bar/'),
+        '/foo'
+      )
+    ).to.be.equal('https://cdn.ampproject.org/bar/foo');
+  });
+
+  it('should add path before query params', () => {
+    expect(
+      appendPathToUrl(
+        urlService.parse('https://cdn.ampproject.org?a=b'),
+        '/foo'
+      )
+    ).to.be.equal('https://cdn.ampproject.org/foo?a=b');
+  });
+
+  it('should add path before fragment', () => {
+    expect(
+      appendPathToUrl(
+        urlService.parse('https://cdn.ampproject.org/#hello'),
+        '/foo'
+      )
+    ).to.be.equal('https://cdn.ampproject.org/foo#hello');
+  });
+
+  it('should add path before query params and fragment', () => {
+    expect(
+      appendPathToUrl(
+        urlService.parse('https://cdn.ampproject.org?a=b#hello'),
+        'foo'
+      )
+    ).to.be.equal('https://cdn.ampproject.org/foo?a=b#hello');
+  });
+});
diff --git a/third_party/amp-toolbox-cache-url/package.json b/third_party/amp-toolbox-cache-url/package.json
index abf41f1244fe..fdf0a4e4cec2 100644
--- a/third_party/amp-toolbox-cache-url/package.json
+++ b/third_party/amp-toolbox-cache-url/package.json
@@ -33,14 +33,14 @@
   },
   "devDependencies": {
     "@ampproject/rollup-plugin-closure-compiler": "0.25.2",
-    "eslint": "6.8.0",
+    "eslint": "7.0.0",
     "eslint-config-google": "0.14.0",
     "jasmine": "3.5.0",
-    "karma": "5.0.4",
+    "karma": "5.0.5",
     "karma-chrome-launcher": "3.1.0",
     "karma-jasmine": "3.1.1",
     "npm-run-all": "4.1.5",
-    "rollup": "2.7.5",
+    "rollup": "2.9.1",
     "rollup-plugin-commonjs": "10.1.0",
     "rollup-plugin-filesize": "8.0.2",
     "rollup-plugin-ignore": "1.0.5",
diff --git a/tools/experiments/experiments-config.js b/tools/experiments/experiments-config.js
index 7a3e7deffb4a..97351a0893f8 100644
--- a/tools/experiments/experiments-config.js
+++ b/tools/experiments/experiments-config.js
@@ -241,14 +241,6 @@ export const EXPERIMENTS = [
     spec: 'https://github.com/ampproject/amphtml/issues/17475',
     cleanupIssue: 'https://github.com/ampproject/amphtml/issues/18897',
   },
-  {
-    id: 'inabox-viewport-friendly',
-    name:
-      'Inabox viewport measures the host window directly if ' +
-      'within friendly iframe',
-    spec: 'https://github.com/ampproject/amphtml/issues/19869',
-    cleanupIssue: 'TODO',
-  },
   {
     id: 'amp-user-location',
     name:
diff --git a/validator/AUTHORS b/validator/AUTHORS
deleted file mode 100644
index ccc1dd378b9f..000000000000
--- a/validator/AUTHORS
+++ /dev/null
@@ -1,6 +0,0 @@
-# This is a list of contributors to AMP HTML.
-
-# Names should be added to this file like so:
-# Name or Organization <email address>
-
-Google Inc.
diff --git a/validator/nodejs/index.js b/validator/nodejs/index.js
index 15f42d24afa2..6797e018907c 100755
--- a/validator/nodejs/index.js
+++ b/validator/nodejs/index.js
@@ -497,4 +497,4 @@ function main() {
       });
 }
 
-exports.main = main
+exports.main = main;
diff --git a/validator/package.json b/validator/package.json
index c80f54093734..ca8f05adc3a6 100644
--- a/validator/package.json
+++ b/validator/package.json
@@ -12,8 +12,8 @@
     "preinstall": "node ../build-system/common/check-package-manager.js"
   },
   "devDependencies": {
-    "google-closure-compiler": "20200426.0.0",
-    "google-closure-library": "20200406.0.0",
+    "google-closure-compiler": "20200504.0.0",
+    "google-closure-library": "20200504.0.0",
     "jasmine": "3.5.0"
   },
   "resolutions": {
diff --git a/validator/yarn.lock b/validator/yarn.lock
index 2346ce25ff9e..ebcaaba6258a 100644
--- a/validator/yarn.lock
+++ b/validator/yarn.lock
@@ -111,51 +111,51 @@ glob@^7.1.4:
     once "^1.3.0"
     path-is-absolute "^1.0.0"
 
-google-closure-compiler-java@^20200426.0.0:
-  version "20200426.0.0"
-  resolved "https://registry.yarnpkg.com/google-closure-compiler-java/-/google-closure-compiler-java-20200426.0.0.tgz#6ea69d2d3dabf329bcaa32fb4ceb51ed2bef734b"
-  integrity sha512-WJSUokSHYQ6iXx3oPnMyF6BSTqU4F3WrNNWB4bnJAXZ2vpjvwtnV0fcSKJ9zjruQteSq3ei657fvpHSbtiT1+g==
-
-google-closure-compiler-js@^20200426.0.0:
-  version "20200426.0.0"
-  resolved "https://registry.yarnpkg.com/google-closure-compiler-js/-/google-closure-compiler-js-20200426.0.0.tgz#b902338c02feb1be799022533c6ac7d281e143bd"
-  integrity sha512-vANCgFDKYvdnD0sX8lsUV/VeGT7xaKIirW8YJ/aaTlR6Qb52yeqFVAnUfzLCggEFPQEyhB+PQatNMI9fn+AL8g==
-
-google-closure-compiler-linux@^20200426.0.0:
-  version "20200426.0.0"
-  resolved "https://registry.yarnpkg.com/google-closure-compiler-linux/-/google-closure-compiler-linux-20200426.0.0.tgz#c724c5e134cea57c60b70664e0b87dc3cedbf8fe"
-  integrity sha512-wY2TK7UV2ChMPGrPKi0rF+NGRG9x8aUo/FbNODj78327u0+RLDAkMfIyghepMbplKMco4dCSht3Yj3v60ScQJQ==
-
-google-closure-compiler-osx@^20200426.0.0:
-  version "20200426.0.0"
-  resolved "https://registry.yarnpkg.com/google-closure-compiler-osx/-/google-closure-compiler-osx-20200426.0.0.tgz#7c9d0f3e1502945675abd7e3fdae5a8ed648217c"
-  integrity sha512-NyJR5opMsoR47oQnU7lOde2doywC9PDYelWOfvnL3AU0sESk3Buiwzwx/xt/lIzkAXdcZkVaCv9b9onbDFdHBA==
-
-google-closure-compiler-windows@^20200426.0.0:
-  version "20200426.0.0"
-  resolved "https://registry.yarnpkg.com/google-closure-compiler-windows/-/google-closure-compiler-windows-20200426.0.0.tgz#e8e9522a1fcb9c31c8448765fd8701fa1adf9099"
-  integrity sha512-ekhN2ruyBsP9jhx9ne8AaWfOSJU4Ph+nWfX454WpRg9rN6wtl+0bhWKyuBquoi5W23YUcmPIKSe9i7j/zDa06w==
-
-google-closure-compiler@20200426.0.0:
-  version "20200426.0.0"
-  resolved "https://registry.yarnpkg.com/google-closure-compiler/-/google-closure-compiler-20200426.0.0.tgz#3ff403e44765dcb8d6bdb3fedd996f49e6dfc2d4"
-  integrity sha512-EvNDnhJ0lTwcDzky7OOvNBbXEs94YU1j0HVuNaosfY6sl+uPE32Sy306d4Uqdixj+mlc/g+6QNppTyQTmeXDow==
+google-closure-compiler-java@^20200504.0.0:
+  version "20200504.0.0"
+  resolved "https://registry.yarnpkg.com/google-closure-compiler-java/-/google-closure-compiler-java-20200504.0.0.tgz#07504ec6f82b181ac9600f6dc7ceedf9d298c014"
+  integrity sha512-7E5rg8dAfpzeTsGuWpwW/ZILVoItFAw4I9AjutY3ujZIadUnlQ6hKHasyvXCB2y1Vzlvf/vsbyjoNvPPZ6IeNA==
+
+google-closure-compiler-js@^20200504.0.0:
+  version "20200504.0.0"
+  resolved "https://registry.yarnpkg.com/google-closure-compiler-js/-/google-closure-compiler-js-20200504.0.0.tgz#858fe15704e168185bcee3585247dd06f5b6fb90"
+  integrity sha512-+03QX239BszaF/tpBYOT5JLR2yAwRoy5ObmwI1zeq9gq+zveD8w7mISWMY+I/3HYef7blN+aMKi78ulE3Mnyww==
+
+google-closure-compiler-linux@^20200504.0.0:
+  version "20200504.0.0"
+  resolved "https://registry.yarnpkg.com/google-closure-compiler-linux/-/google-closure-compiler-linux-20200504.0.0.tgz#435643e4b06cdb628da649b25cc0895b9583c0fc"
+  integrity sha512-DljGPGILaebP6XdykflPwzwYrpi3lamfIx7FNjjhqM0ukHOBUyRfEW8E87sjSwCgvQFHqUn3CB39JhLEcf15UA==
+
+google-closure-compiler-osx@^20200504.0.0:
+  version "20200504.0.0"
+  resolved "https://registry.yarnpkg.com/google-closure-compiler-osx/-/google-closure-compiler-osx-20200504.0.0.tgz#0bb68d18d2f8f4f0742975aaffed4927e826b81c"
+  integrity sha512-isez2ZP42xLkIMd+HgD+DkazHfXNsmCwn6wC7LWlBG56vVM2NoBXTjNn+uPjLFJ0M+wzhlwIVhJnMF+qORH2Sw==
+
+google-closure-compiler-windows@^20200504.0.0:
+  version "20200504.0.0"
+  resolved "https://registry.yarnpkg.com/google-closure-compiler-windows/-/google-closure-compiler-windows-20200504.0.0.tgz#d9d237b71d06a3a7828845aff03c6302c6351a58"
+  integrity sha512-T5g2Slv6W/SO4RhAZcp6neWbZCQ8B0QXujvqLbx331r7uMxM7IaScHTNry6NTFFwReiY28COIqSuyEPuGmFjDg==
+
+google-closure-compiler@20200504.0.0:
+  version "20200504.0.0"
+  resolved "https://registry.yarnpkg.com/google-closure-compiler/-/google-closure-compiler-20200504.0.0.tgz#dfd2eb6b40d060ce0a0f08a8afa7db39a9f4e09e"
+  integrity sha512-No343xYZ/d5+f7VPBm1Vy6TjcUSpP3b0VYe3lww5M5bonEnyF6jwCuGhYfwtpCnM92ZSVcLqbJJA8SDf5DvSZA==
   dependencies:
     chalk "2.x"
-    google-closure-compiler-java "^20200426.0.0"
-    google-closure-compiler-js "^20200426.0.0"
+    google-closure-compiler-java "^20200504.0.0"
+    google-closure-compiler-js "^20200504.0.0"
     minimist "1.x"
     vinyl "2.x"
     vinyl-sourcemaps-apply "^0.2.0"
   optionalDependencies:
-    google-closure-compiler-linux "^20200426.0.0"
-    google-closure-compiler-osx "^20200426.0.0"
-    google-closure-compiler-windows "^20200426.0.0"
-
-google-closure-library@20200406.0.0:
-  version "20200406.0.0"
-  resolved "https://registry.yarnpkg.com/google-closure-library/-/google-closure-library-20200406.0.0.tgz#6a47652b9c72e14c94f0dd5de9ea7e8792cf58f6"
-  integrity sha512-gk6TI6sRVfL3aAFxtVu6BaQp3/eWVmpvY1RWmwFcCGFNQ8qYAudFE/OqPDSr/bNrf9H1/OgOh71oEwpuMerqCA==
+    google-closure-compiler-linux "^20200504.0.0"
+    google-closure-compiler-osx "^20200504.0.0"
+    google-closure-compiler-windows "^20200504.0.0"
+
+google-closure-library@20200504.0.0:
+  version "20200504.0.0"
+  resolved "https://registry.yarnpkg.com/google-closure-library/-/google-closure-library-20200504.0.0.tgz#3171065fe70cfa0968aadf210d851ecd34fb0eb0"
+  integrity sha512-9wwe6WWIR2jMT4IvXVH7CctCpwzeViIjMjQakxRu0DVBlFCRGAVQOnWaVABZwdR/JglQBcjBF+0JzpXZ41KY/A==
 
 growl@^1.10.0:
   version "1.10.5"
diff --git a/yarn.lock b/yarn.lock
index 0f6638c84f30..2bbec109e3e2 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -2162,10 +2162,10 @@ acorn-jsx@^5.0.2:
   resolved "https://registry.yarnpkg.com/acorn-jsx/-/acorn-jsx-5.0.2.tgz#84b68ea44b373c4f8686023a551f61a21b7c4a4f"
   integrity sha512-tiNTrP1MP0QrChmD2DdupCr6HWSFeKVw5d/dHTu4Y7rkAkRhU/Dt7dphAfIUyxtHpl/eBVip5uTNSpQJHylpAw==
 
-acorn-jsx@^5.1.0:
-  version "5.1.0"
-  resolved "https://registry.yarnpkg.com/acorn-jsx/-/acorn-jsx-5.1.0.tgz#294adb71b57398b0680015f0a38c563ee1db5384"
-  integrity sha512-tMUqwBWfLFbJbizRmEcWSLw6HnFzfdJs2sOJEOwwtVPMoH/0Ay+E703oZz78VSXZiiDcZrQ5XKjPIUQixhmgVw==
+acorn-jsx@^5.2.0:
+  version "5.2.0"
+  resolved "https://registry.yarnpkg.com/acorn-jsx/-/acorn-jsx-5.2.0.tgz#4c66069173d6fdd68ed85239fc256226182b2ebe"
+  integrity sha512-HiUX/+K2YpkpJ+SzBffkM/AQ2YE03S0U1kjTLVpoJdhZMOWy8qvXVN9JdLqv2QsaQ6MPYQIuNmwD8zOiYUofLQ==
 
 acorn-node@^1.2.0, acorn-node@^1.3.0, acorn-node@^1.5.2, acorn-node@^1.6.1:
   version "1.8.2"
@@ -2201,7 +2201,7 @@ acorn@^6.0.1:
   resolved "https://registry.yarnpkg.com/acorn/-/acorn-6.3.0.tgz#0087509119ffa4fc0a0041d1e93a417e68cb856e"
   integrity sha512-/czfa8BwS88b9gWQVhc8eknunSA2DoJpJyTQkhheIf5E48u1N0R4q/YxxsAeqRrmK9TQ/uYfgLDfZo91UlANIA==
 
-acorn@^7.0.0, acorn@^7.1.0:
+acorn@^7.0.0:
   version "7.1.0"
   resolved "https://registry.yarnpkg.com/acorn/-/acorn-7.1.0.tgz#949d36f2c292535da602283586c2477c57eb2d6c"
   integrity sha512-kL5CuoXA/dgxlBbVrflsflzQ3PAas7RYZB52NOm/6839iVYJgKMJ3cQJD+t2i5+qFa8h3MDpEOJiS64E8JLnSQ==
@@ -2291,10 +2291,10 @@ amdefine@>=0.0.4:
   resolved "https://registry.yarnpkg.com/amdefine/-/amdefine-1.0.1.tgz#4a5282ac164729e93619bcfd3ad151f817ce91f5"
   integrity sha1-SlKCrBZHKek2Gbz9OtFR+BfOkfU=
 
-amphtml-validator@1.0.30:
-  version "1.0.30"
-  resolved "https://registry.yarnpkg.com/amphtml-validator/-/amphtml-validator-1.0.30.tgz#b722ea5e965d0cc028cbdc360fc76b97e669715e"
-  integrity sha512-CaEm2ivIi4M4QTiFnCE9t4MRgawCf88iAV/+VsS0zEw6T4VBU6zoXcgn4L+dt6/WZ/NYxKpc38duSoRLqZJhNQ==
+amphtml-validator@1.0.31:
+  version "1.0.31"
+  resolved "https://registry.yarnpkg.com/amphtml-validator/-/amphtml-validator-1.0.31.tgz#cf926ad4bbefd720b4cbeef6221f794f35849ac6"
+  integrity sha512-GEVZeUJqm2ssLLrERi3Zeyk6TEQlvMGRxKqkgQMt2IvyYiGEWLbwp5K6UfX6cD9aCc1xqbk9n+rDBi4HZv3uOQ==
   dependencies:
     colors "1.2.5"
     commander "2.15.1"
@@ -4435,10 +4435,10 @@ commander@~2.1.0:
   resolved "https://registry.yarnpkg.com/commander/-/commander-2.1.0.tgz#d121bbae860d9992a3d517ba96f56588e47c6781"
   integrity sha1-0SG7roYNmZKj1Re6lvVliOR8Z4E=
 
-comment-parser@^0.7.2:
-  version "0.7.2"
-  resolved "https://registry.yarnpkg.com/comment-parser/-/comment-parser-0.7.2.tgz#baf6d99b42038678b81096f15b630d18142f4b8a"
-  integrity sha512-4Rjb1FnxtOcv9qsfuaNuVsmmVn4ooVoBHzYfyKteiXwIU84PClyGA5jASoFMwPV93+FPh9spwueXauxFJZkGAg==
+comment-parser@^0.7.4:
+  version "0.7.4"
+  resolved "https://registry.yarnpkg.com/comment-parser/-/comment-parser-0.7.4.tgz#f5eb83cbae323cae6533c057f41d52692361c83a"
+  integrity sha512-Nnl77/mt6sj1BiYSVMeMWzvD0183F2MFOJyFRmZHimUVDYS9J40AvXpiFA7RpU5pQH+HkvYc0dnsHpwW2xmbyQ==
 
 common-path-prefix@^1.0.0:
   version "1.0.0"
@@ -4807,6 +4807,15 @@ cross-spawn@^7.0.0:
     shebang-command "^2.0.0"
     which "^2.0.1"
 
+cross-spawn@^7.0.2:
+  version "7.0.2"
+  resolved "https://registry.yarnpkg.com/cross-spawn/-/cross-spawn-7.0.2.tgz#d0d7dcfa74e89115c7619f4f721a94e1fdb716d6"
+  integrity sha512-PD6G8QG3S4FK/XCGFbEQrDqO2AnMMsy0meR7lerlIOHAAbkuavGU/pOqprrlvfTNjvowivTeBsjebAL0NSoMxw==
+  dependencies:
+    path-key "^3.1.0"
+    shebang-command "^2.0.0"
+    which "^2.0.1"
+
 crypto-browserify@^3.0.0:
   version "3.12.0"
   resolved "https://registry.yarnpkg.com/crypto-browserify/-/crypto-browserify-3.12.0.tgz#396cf9f3137f03e4b8e532c58f698254e00f80ec"
@@ -6112,12 +6121,12 @@ eslint-plugin-jasmine@4.1.1:
   resolved "https://registry.yarnpkg.com/eslint-plugin-jasmine/-/eslint-plugin-jasmine-4.1.1.tgz#afdf8ca6a91e85041d9e0fb650af446874bf8852"
   integrity sha512-uS7kvt7RPUB/gLDwhJ/Ax0APrmkj7In8VJWkiZLYHafz2Ix74mMRJx82YZZ3zHRa/YOuTL+ig6dW/aKwdNzUuw==
 
-eslint-plugin-jsdoc@24.0.2:
-  version "24.0.2"
-  resolved "https://registry.yarnpkg.com/eslint-plugin-jsdoc/-/eslint-plugin-jsdoc-24.0.2.tgz#c679c7afac42cf872ffb1a6a246b5518b7b8eed4"
-  integrity sha512-tvk/jPpIP6MBVZETYnurKL/VGKzSinSbhpz1x+CzDOX20bmhRnCiexrgre4xF0WD/feg7ARKTVLCygVB3pfG5Q==
+eslint-plugin-jsdoc@24.0.6:
+  version "24.0.6"
+  resolved "https://registry.yarnpkg.com/eslint-plugin-jsdoc/-/eslint-plugin-jsdoc-24.0.6.tgz#360f75b7b79a64eb6f072de9f37322588578abf0"
+  integrity sha512-WDzUgShMK7Zg9N6s19LxUqy71At/PxCuMEXaKyBzybhABq6iU4DaZtWZ+4fkCMBvMzMwMAPa2oRD/+fQGORMhg==
   dependencies:
-    comment-parser "^0.7.2"
+    comment-parser "^0.7.4"
     debug "^4.1.1"
     jsdoctypeparser "^6.1.0"
     lodash "^4.17.15"
@@ -6146,10 +6155,10 @@ eslint-plugin-prettier@3.1.3:
   dependencies:
     prettier-linter-helpers "^1.0.0"
 
-eslint-plugin-react-hooks@3.0.0:
-  version "3.0.0"
-  resolved "https://registry.yarnpkg.com/eslint-plugin-react-hooks/-/eslint-plugin-react-hooks-3.0.0.tgz#9e80c71846eb68dd29c3b21d832728aa66e5bd35"
-  integrity sha512-EjxTHxjLKIBWFgDJdhKKzLh5q+vjTFrqNZX36uIxWS4OfyXe5DawqPj3U5qeJ1ngLwatjzQnmR0Lz0J0YH3kxw==
+eslint-plugin-react-hooks@4.0.0:
+  version "4.0.0"
+  resolved "https://registry.yarnpkg.com/eslint-plugin-react-hooks/-/eslint-plugin-react-hooks-4.0.0.tgz#81196b990043cde339e25c6662aeebe32ac52d01"
+  integrity sha512-YKBY+kilK5wrwIdQnCF395Ya6nDro3EAMoe+2xFkmyklyhF16fH83TrQOo9zbZIDxBsXFgBbywta/0JKRNFDkw==
 
 eslint-plugin-react@7.19.0:
   version "7.19.0"
@@ -6196,10 +6205,10 @@ eslint-utils@^1.4.2:
   dependencies:
     eslint-visitor-keys "^1.0.0"
 
-eslint-utils@^1.4.3:
-  version "1.4.3"
-  resolved "https://registry.yarnpkg.com/eslint-utils/-/eslint-utils-1.4.3.tgz#74fec7c54d0776b6f67e0251040b5806564e981f"
-  integrity sha512-fbBN5W2xdY45KulGXmLHZ3c3FHfVYmKg0IrAKGOkT/464PQsx2UeIzfz1RmEci+KLm1bBaAzZAh8+/E+XAeZ8Q==
+eslint-utils@^2.0.0:
+  version "2.0.0"
+  resolved "https://registry.yarnpkg.com/eslint-utils/-/eslint-utils-2.0.0.tgz#7be1cc70f27a72a76cd14aa698bcabed6890e1cd"
+  integrity sha512-0HCPuJv+7Wv1bACm8y5/ECVfYdfsAm9xmVb7saeFlxjPYALefjhbYoCkBjPdPzGH8wWyTpAez82Fh3VKYEZ8OA==
   dependencies:
     eslint-visitor-keys "^1.1.0"
 
@@ -6208,22 +6217,22 @@ eslint-visitor-keys@^1.0.0, eslint-visitor-keys@^1.1.0:
   resolved "https://registry.yarnpkg.com/eslint-visitor-keys/-/eslint-visitor-keys-1.1.0.tgz#e2a82cea84ff246ad6fb57f9bde5b46621459ec2"
   integrity sha512-8y9YjtM1JBJU/A9Kc+SbaOV4y29sSWckBwMHa+FGtVj5gN/sbnKDf6xJUl+8g7FAij9LVaP8C24DUiH/f/2Z9A==
 
-eslint@6.8.0:
-  version "6.8.0"
-  resolved "https://registry.yarnpkg.com/eslint/-/eslint-6.8.0.tgz#62262d6729739f9275723824302fb227c8c93ffb"
-  integrity sha512-K+Iayyo2LtyYhDSYwz5D5QdWw0hCacNzyq1Y821Xna2xSJj7cijoLLYmLxTQgcgZ9mC61nryMy9S7GRbYpI5Ig==
+eslint@7.0.0:
+  version "7.0.0"
+  resolved "https://registry.yarnpkg.com/eslint/-/eslint-7.0.0.tgz#c35dfd04a4372110bd78c69a8d79864273919a08"
+  integrity sha512-qY1cwdOxMONHJfGqw52UOpZDeqXy8xmD0u8CT6jIstil72jkhURC704W8CFyTPDPllz4z4lu0Ql1+07PG/XdIg==
   dependencies:
     "@babel/code-frame" "^7.0.0"
     ajv "^6.10.0"
-    chalk "^2.1.0"
-    cross-spawn "^6.0.5"
+    chalk "^4.0.0"
+    cross-spawn "^7.0.2"
     debug "^4.0.1"
     doctrine "^3.0.0"
     eslint-scope "^5.0.0"
-    eslint-utils "^1.4.3"
+    eslint-utils "^2.0.0"
     eslint-visitor-keys "^1.1.0"
-    espree "^6.1.2"
-    esquery "^1.0.1"
+    espree "^7.0.0"
+    esquery "^1.2.0"
     esutils "^2.0.2"
     file-entry-cache "^5.0.1"
     functional-red-black-tree "^1.0.1"
@@ -6236,17 +6245,16 @@ eslint@6.8.0:
     is-glob "^4.0.0"
     js-yaml "^3.13.1"
     json-stable-stringify-without-jsonify "^1.0.1"
-    levn "^0.3.0"
+    levn "^0.4.1"
     lodash "^4.17.14"
     minimatch "^3.0.4"
-    mkdirp "^0.5.1"
     natural-compare "^1.4.0"
-    optionator "^0.8.3"
+    optionator "^0.9.1"
     progress "^2.0.0"
-    regexpp "^2.0.1"
-    semver "^6.1.2"
-    strip-ansi "^5.2.0"
-    strip-json-comments "^3.0.1"
+    regexpp "^3.1.0"
+    semver "^7.2.1"
+    strip-ansi "^6.0.0"
+    strip-json-comments "^3.1.0"
     table "^5.2.3"
     text-table "^0.2.0"
     v8-compile-cache "^2.0.3"
@@ -6318,13 +6326,13 @@ espree@^6.1.1:
     acorn-jsx "^5.0.2"
     eslint-visitor-keys "^1.1.0"
 
-espree@^6.1.2:
-  version "6.1.2"
-  resolved "https://registry.yarnpkg.com/espree/-/espree-6.1.2.tgz#6c272650932b4f91c3714e5e7b5f5e2ecf47262d"
-  integrity sha512-2iUPuuPP+yW1PZaMSDM9eyVf8D5P0Hi8h83YtZ5bPc/zHYjII5khoixIUTMO794NOY8F/ThF1Bo8ncZILarUTA==
+espree@^7.0.0:
+  version "7.0.0"
+  resolved "https://registry.yarnpkg.com/espree/-/espree-7.0.0.tgz#8a7a60f218e69f120a842dc24c5a88aa7748a74e"
+  integrity sha512-/r2XEx5Mw4pgKdyb7GNLQNsu++asx/dltf/CI8RFi9oGHxmQFgvLbc5Op4U6i8Oaj+kdslhJtVlEZeAqH5qOTw==
   dependencies:
-    acorn "^7.1.0"
-    acorn-jsx "^5.1.0"
+    acorn "^7.1.1"
+    acorn-jsx "^5.2.0"
     eslint-visitor-keys "^1.1.0"
 
 esprima@1.1.x, esprima@~1.1.1:
@@ -6361,6 +6369,13 @@ esquery@^1.0.1:
   dependencies:
     estraverse "^4.0.0"
 
+esquery@^1.2.0:
+  version "1.3.1"
+  resolved "https://registry.yarnpkg.com/esquery/-/esquery-1.3.1.tgz#b78b5828aa8e214e29fb74c4d5b752e1c033da57"
+  integrity sha512-olpvt9QG0vniUBZspVRN6lwB7hOZoTRtT+jzR+tS4ffYx2mzbw+z0XCOk44aaLYKApNX5nMm+E+P6o25ip/DHQ==
+  dependencies:
+    estraverse "^5.1.0"
+
 esrecurse@^4.1.0:
   version "4.2.1"
   resolved "https://registry.yarnpkg.com/esrecurse/-/esrecurse-4.2.1.tgz#007a3b9fdbc2b3bb87e4879ea19c92fdbd3942cf"
@@ -6378,6 +6393,11 @@ estraverse@^4.0.0, estraverse@^4.1.0, estraverse@^4.1.1, estraverse@^4.2.0:
   resolved "https://registry.yarnpkg.com/estraverse/-/estraverse-4.3.0.tgz#398ad3f3c5a24948be7725e83d11a7de28cdbd1d"
   integrity sha512-39nnKffWz8xN1BU/2c79n9nB9HDzo0niYUqx6xyqUnyoAnQyyWpOTdZEeiCch8BBu515t4wp9ZmgVfVhn9EBpw==
 
+estraverse@^5.1.0:
+  version "5.1.0"
+  resolved "https://registry.yarnpkg.com/estraverse/-/estraverse-5.1.0.tgz#374309d39fd935ae500e7b92e8a6b4c720e59642"
+  integrity sha512-FyohXK+R0vE+y1nHLoBM7ZTyqRpqAlhdZHCWIWEviFLiGB8b04H6bQs8G+XTthacvT8VuwvteiP7RJSxMs8UEw==
+
 estraverse@~1.5.0:
   version "1.5.1"
   resolved "https://registry.yarnpkg.com/estraverse/-/estraverse-1.5.1.tgz#867a3e8e58a9f84618afb6c2ddbcd916b7cbaf71"
@@ -6754,7 +6774,7 @@ fast-json-stable-stringify@^2.0.0:
   resolved "https://registry.yarnpkg.com/fast-json-stable-stringify/-/fast-json-stable-stringify-2.0.0.tgz#d5142c0caee6b1189f87d3a76111064f86c8bbf2"
   integrity sha1-1RQsDK7msRifh9OnYREGT4bIu/I=
 
-fast-levenshtein@~2.0.4, fast-levenshtein@~2.0.6:
+fast-levenshtein@^2.0.6, fast-levenshtein@~2.0.4:
   version "2.0.6"
   resolved "https://registry.yarnpkg.com/fast-levenshtein/-/fast-levenshtein-2.0.6.tgz#3d8a5c66883a16a30ca8643e851f19baa7797917"
   integrity sha1-PYpcZog6FqMMqGQ+hR8Zuqd5eRc=
@@ -6793,10 +6813,10 @@ fbjs@^0.8.4:
     setimmediate "^1.0.5"
     ua-parser-js "^0.7.18"
 
-fetch-mock@9.4.0:
-  version "9.4.0"
-  resolved "https://registry.yarnpkg.com/fetch-mock/-/fetch-mock-9.4.0.tgz#9be073577bcfa57af714ca91f7536aff8450ec88"
-  integrity sha512-tqnFmcjYheW5Z9zOPRVY+ZXjB/QWCYtPiOrYGEsPgKfpGHco97eaaj7Rv9MjK7PVWG4rWfv6t2IgQAzDQizBZA==
+fetch-mock@9.5.1:
+  version "9.5.1"
+  resolved "https://registry.yarnpkg.com/fetch-mock/-/fetch-mock-9.5.1.tgz#85ff98803e2cbdf3e083dd582ee27896505d0e91"
+  integrity sha512-d4pfS9CA3gQgWNBO6zmWyj5EQ+W/xPWUw8iWrr7+nVaj4aIqBRNMoGx81E9i6aFbGAsuYwGKXyLcQ3y9D5/JwA==
   dependencies:
     babel-runtime "^6.26.0"
     core-js "^3.0.0"
@@ -7468,46 +7488,46 @@ glogg@^1.0.0:
   dependencies:
     sparkles "^1.0.0"
 
-google-closure-compiler-java@^20200426.0.0:
-  version "20200426.0.0"
-  resolved "https://registry.yarnpkg.com/google-closure-compiler-java/-/google-closure-compiler-java-20200426.0.0.tgz#6ea69d2d3dabf329bcaa32fb4ceb51ed2bef734b"
-  integrity sha512-WJSUokSHYQ6iXx3oPnMyF6BSTqU4F3WrNNWB4bnJAXZ2vpjvwtnV0fcSKJ9zjruQteSq3ei657fvpHSbtiT1+g==
+google-closure-compiler-java@^20200504.0.0:
+  version "20200504.0.0"
+  resolved "https://registry.yarnpkg.com/google-closure-compiler-java/-/google-closure-compiler-java-20200504.0.0.tgz#07504ec6f82b181ac9600f6dc7ceedf9d298c014"
+  integrity sha512-7E5rg8dAfpzeTsGuWpwW/ZILVoItFAw4I9AjutY3ujZIadUnlQ6hKHasyvXCB2y1Vzlvf/vsbyjoNvPPZ6IeNA==
 
-google-closure-compiler-js@^20200426.0.0:
-  version "20200426.0.0"
-  resolved "https://registry.yarnpkg.com/google-closure-compiler-js/-/google-closure-compiler-js-20200426.0.0.tgz#b902338c02feb1be799022533c6ac7d281e143bd"
-  integrity sha512-vANCgFDKYvdnD0sX8lsUV/VeGT7xaKIirW8YJ/aaTlR6Qb52yeqFVAnUfzLCggEFPQEyhB+PQatNMI9fn+AL8g==
+google-closure-compiler-js@^20200504.0.0:
+  version "20200504.0.0"
+  resolved "https://registry.yarnpkg.com/google-closure-compiler-js/-/google-closure-compiler-js-20200504.0.0.tgz#858fe15704e168185bcee3585247dd06f5b6fb90"
+  integrity sha512-+03QX239BszaF/tpBYOT5JLR2yAwRoy5ObmwI1zeq9gq+zveD8w7mISWMY+I/3HYef7blN+aMKi78ulE3Mnyww==
 
-google-closure-compiler-linux@^20200426.0.0:
-  version "20200426.0.0"
-  resolved "https://registry.yarnpkg.com/google-closure-compiler-linux/-/google-closure-compiler-linux-20200426.0.0.tgz#c724c5e134cea57c60b70664e0b87dc3cedbf8fe"
-  integrity sha512-wY2TK7UV2ChMPGrPKi0rF+NGRG9x8aUo/FbNODj78327u0+RLDAkMfIyghepMbplKMco4dCSht3Yj3v60ScQJQ==
+google-closure-compiler-linux@^20200504.0.0:
+  version "20200504.0.0"
+  resolved "https://registry.yarnpkg.com/google-closure-compiler-linux/-/google-closure-compiler-linux-20200504.0.0.tgz#435643e4b06cdb628da649b25cc0895b9583c0fc"
+  integrity sha512-DljGPGILaebP6XdykflPwzwYrpi3lamfIx7FNjjhqM0ukHOBUyRfEW8E87sjSwCgvQFHqUn3CB39JhLEcf15UA==
 
-google-closure-compiler-osx@^20200426.0.0:
-  version "20200426.0.0"
-  resolved "https://registry.yarnpkg.com/google-closure-compiler-osx/-/google-closure-compiler-osx-20200426.0.0.tgz#7c9d0f3e1502945675abd7e3fdae5a8ed648217c"
-  integrity sha512-NyJR5opMsoR47oQnU7lOde2doywC9PDYelWOfvnL3AU0sESk3Buiwzwx/xt/lIzkAXdcZkVaCv9b9onbDFdHBA==
+google-closure-compiler-osx@^20200504.0.0:
+  version "20200504.0.0"
+  resolved "https://registry.yarnpkg.com/google-closure-compiler-osx/-/google-closure-compiler-osx-20200504.0.0.tgz#0bb68d18d2f8f4f0742975aaffed4927e826b81c"
+  integrity sha512-isez2ZP42xLkIMd+HgD+DkazHfXNsmCwn6wC7LWlBG56vVM2NoBXTjNn+uPjLFJ0M+wzhlwIVhJnMF+qORH2Sw==
 
-google-closure-compiler-windows@^20200426.0.0:
-  version "20200426.0.0"
-  resolved "https://registry.yarnpkg.com/google-closure-compiler-windows/-/google-closure-compiler-windows-20200426.0.0.tgz#e8e9522a1fcb9c31c8448765fd8701fa1adf9099"
-  integrity sha512-ekhN2ruyBsP9jhx9ne8AaWfOSJU4Ph+nWfX454WpRg9rN6wtl+0bhWKyuBquoi5W23YUcmPIKSe9i7j/zDa06w==
+google-closure-compiler-windows@^20200504.0.0:
+  version "20200504.0.0"
+  resolved "https://registry.yarnpkg.com/google-closure-compiler-windows/-/google-closure-compiler-windows-20200504.0.0.tgz#d9d237b71d06a3a7828845aff03c6302c6351a58"
+  integrity sha512-T5g2Slv6W/SO4RhAZcp6neWbZCQ8B0QXujvqLbx331r7uMxM7IaScHTNry6NTFFwReiY28COIqSuyEPuGmFjDg==
 
-google-closure-compiler@20200426.0.0:
-  version "20200426.0.0"
-  resolved "https://registry.yarnpkg.com/google-closure-compiler/-/google-closure-compiler-20200426.0.0.tgz#3ff403e44765dcb8d6bdb3fedd996f49e6dfc2d4"
-  integrity sha512-EvNDnhJ0lTwcDzky7OOvNBbXEs94YU1j0HVuNaosfY6sl+uPE32Sy306d4Uqdixj+mlc/g+6QNppTyQTmeXDow==
+google-closure-compiler@20200504.0.0:
+  version "20200504.0.0"
+  resolved "https://registry.yarnpkg.com/google-closure-compiler/-/google-closure-compiler-20200504.0.0.tgz#dfd2eb6b40d060ce0a0f08a8afa7db39a9f4e09e"
+  integrity sha512-No343xYZ/d5+f7VPBm1Vy6TjcUSpP3b0VYe3lww5M5bonEnyF6jwCuGhYfwtpCnM92ZSVcLqbJJA8SDf5DvSZA==
   dependencies:
     chalk "2.x"
-    google-closure-compiler-java "^20200426.0.0"
-    google-closure-compiler-js "^20200426.0.0"
+    google-closure-compiler-java "^20200504.0.0"
+    google-closure-compiler-js "^20200504.0.0"
     minimist "1.x"
     vinyl "2.x"
     vinyl-sourcemaps-apply "^0.2.0"
   optionalDependencies:
-    google-closure-compiler-linux "^20200426.0.0"
-    google-closure-compiler-osx "^20200426.0.0"
-    google-closure-compiler-windows "^20200426.0.0"
+    google-closure-compiler-linux "^20200504.0.0"
+    google-closure-compiler-osx "^20200504.0.0"
+    google-closure-compiler-windows "^20200504.0.0"
 
 got@^9.6.0:
   version "9.6.0"
@@ -10274,10 +10294,10 @@ karma-super-dots-reporter@0.2.0:
     chalk "^0.5.1"
     log-symbols "^1.0.1"
 
-karma@5.0.4:
-  version "5.0.4"
-  resolved "https://registry.yarnpkg.com/karma/-/karma-5.0.4.tgz#b374a1e541ad66da668460b99c6faf20cfffc97a"
-  integrity sha512-UGqTe2LBiGQBXRN+Fygeiq63tbfOX45639SKSbPkLpARwnxROWJZg+froGkpHxr84FXCe8UGCf+1PITM6frT5w==
+karma@5.0.5:
+  version "5.0.5"
+  resolved "https://registry.yarnpkg.com/karma/-/karma-5.0.5.tgz#f7716f459f354734a7856ef9ed67fe0a38270aa4"
+  integrity sha512-Q4Su7kNwkTgqS+KbSCYgH0p4a/0JIxVLyp7qKNV7vgPNhIF4kIoh0GlUfMKpw67BrR3hgPQSJoxgF7xnzUtPpg==
   dependencies:
     body-parser "^1.16.1"
     braces "^3.0.2"
@@ -10444,6 +10464,14 @@ levn@^0.3.0, levn@~0.3.0:
     prelude-ls "~1.1.2"
     type-check "~0.3.2"
 
+levn@^0.4.1:
+  version "0.4.1"
+  resolved "https://registry.yarnpkg.com/levn/-/levn-0.4.1.tgz#ae4562c007473b932a6200d403268dd2fffc6ade"
+  integrity sha512-+bT2uH4E5LGE7h/n3evcS/sQlJXCpIp6ym8OWJ5eV6+67Dsql/LaaT7qJBAt2rzfoa/5QBGBhxDix1dMt2kQKQ==
+  dependencies:
+    prelude-ls "^1.2.1"
+    type-check "~0.4.0"
+
 lex-parser@0.1.x, lex-parser@~0.1.3:
   version "0.1.4"
   resolved "https://registry.yarnpkg.com/lex-parser/-/lex-parser-0.1.4.tgz#64c4f025f17fd53bfb45763faeb16f015a747550"
@@ -12020,17 +12048,17 @@ optionator@^0.8.1, optionator@^0.8.2:
     type-check "~0.3.2"
     wordwrap "~1.0.0"
 
-optionator@^0.8.3:
-  version "0.8.3"
-  resolved "https://registry.yarnpkg.com/optionator/-/optionator-0.8.3.tgz#84fa1d036fe9d3c7e21d99884b601167ec8fb495"
-  integrity sha512-+IW9pACdk3XWmmTXG8m3upGUJst5XRGzxMRjXzAuJ1XnIFNvfhjjIuYkDvysnPQ7qzqVzLt78BCruntqRhWQbA==
+optionator@^0.9.1:
+  version "0.9.1"
+  resolved "https://registry.yarnpkg.com/optionator/-/optionator-0.9.1.tgz#4f236a6373dae0566a6d43e1326674f50c291499"
+  integrity sha512-74RlY5FCnhq4jRxVUPKDaRwrVNXMqsGsiW6AJw4XK8hmtm10wC0ypZBLw5IIp85NZMr91+qd1RvvENwg7jjRFw==
   dependencies:
-    deep-is "~0.1.3"
-    fast-levenshtein "~2.0.6"
-    levn "~0.3.0"
-    prelude-ls "~1.1.2"
-    type-check "~0.3.2"
-    word-wrap "~1.2.3"
+    deep-is "^0.1.3"
+    fast-levenshtein "^2.0.6"
+    levn "^0.4.1"
+    prelude-ls "^1.2.1"
+    type-check "^0.4.0"
+    word-wrap "^1.2.3"
 
 options@>=0.0.5:
   version "0.0.6"
@@ -12913,10 +12941,10 @@ postcss-value-parser@^4.0.2, postcss-value-parser@^4.0.3:
   resolved "https://registry.yarnpkg.com/postcss-value-parser/-/postcss-value-parser-4.0.3.tgz#651ff4593aa9eda8d5d0d66593a2417aeaeb325d"
   integrity sha512-N7h4pG+Nnu5BEIzyeaaIYWs0LI5XC40OrRh5L60z0QjFsqGWcHcbkBvpe1WYpcIS9yQ8sOi/vIPt1ejQCrMVrg==
 
-postcss@7.0.29:
-  version "7.0.29"
-  resolved "https://registry.yarnpkg.com/postcss/-/postcss-7.0.29.tgz#d3a903872bd52280b83bce38cdc83ce55c06129e"
-  integrity sha512-ba0ApvR3LxGvRMMiUa9n0WR4HjzcYm7tS+ht4/2Nd0NLtHpPIH77fuB9Xh1/yJVz9O/E/95Y/dn8ygWsyffXtw==
+postcss@7.0.30:
+  version "7.0.30"
+  resolved "https://registry.yarnpkg.com/postcss/-/postcss-7.0.30.tgz#cc9378beffe46a02cbc4506a0477d05fcea9a8e2"
+  integrity sha512-nu/0m+NtIzoubO+xdAlwZl/u5S5vi/y6BCsoL8D+8IxsD3XvBS8X4YEADNIVXKVuQvduiucnRv+vPIqj56EGMQ==
   dependencies:
     chalk "^2.4.2"
     source-map "^0.6.1"
@@ -12963,6 +12991,11 @@ preact@10.2.1:
   resolved "https://registry.yarnpkg.com/preact/-/preact-10.2.1.tgz#b30eb4cdc455499ee2ff82e0fa1a16fc8e20f3a4"
   integrity sha512-BUNvmQcVtNElku7mYHexIiM5JlGNSW2BY9O2t9xk1NqA43O8wbE0cah6PAlvT7PBHvyDRJ5TAj5Fewdi9DqLoQ==
 
+prelude-ls@^1.2.1:
+  version "1.2.1"
+  resolved "https://registry.yarnpkg.com/prelude-ls/-/prelude-ls-1.2.1.tgz#debc6489d7a6e6b0e7611888cec880337d316396"
+  integrity sha512-vkcDPrRZo1QZLbn5RLGPpg/WmIQ65qoWWhcGKf/b5eplkkarX0m9z8ppCat4mlOqUsWpyNuYgO3VRyrYHSzX5g==
+
 prelude-ls@~1.1.2:
   version "1.1.2"
   resolved "https://registry.yarnpkg.com/prelude-ls/-/prelude-ls-1.1.2.tgz#21932a549f5e52ffd9a827f570e04be62a97da54"
@@ -13710,6 +13743,11 @@ regexpp@^2.0.1:
   resolved "https://registry.yarnpkg.com/regexpp/-/regexpp-2.0.1.tgz#8d19d31cf632482b589049f8281f93dbcba4d07f"
   integrity sha512-lv0M6+TkDVniA3aD1Eg0DVpfU/booSu7Eev3TDO/mZKHBfVjgCGTV4t4buppESEYDtkArYFOxTJWv6S5C+iaNw==
 
+regexpp@^3.1.0:
+  version "3.1.0"
+  resolved "https://registry.yarnpkg.com/regexpp/-/regexpp-3.1.0.tgz#206d0ad0a5648cffbdb8ae46438f3dc51c9f78e2"
+  integrity sha512-ZOIzd8yVsQQA7j8GCSlPGXwg5PfmA1mrq0JP4nGhh54LaKN3xdai/vHUDu74pKwV8OxseMS65u2NImosQcSD0Q==
+
 regexpu-core@^4.6.0:
   version "4.6.0"
   resolved "https://registry.yarnpkg.com/regexpu-core/-/regexpu-core-4.6.0.tgz#2037c18b327cfce8a6fea2a4ec441f2432afb8b6"
@@ -15170,6 +15208,11 @@ strip-json-comments@^3.0.1:
   resolved "https://registry.yarnpkg.com/strip-json-comments/-/strip-json-comments-3.0.1.tgz#85713975a91fb87bf1b305cca77395e40d2a64a7"
   integrity sha512-VTyMAUfdm047mwKl+u79WIdrZxtFtn+nBxHeb844XBQ9uMNTuTHdx2hc5RiAJYqwTj3wc/xe5HLSdJSkJ+WfZw==
 
+strip-json-comments@^3.1.0:
+  version "3.1.0"
+  resolved "https://registry.yarnpkg.com/strip-json-comments/-/strip-json-comments-3.1.0.tgz#7638d31422129ecf4457440009fba03f9f9ac180"
+  integrity sha512-e6/d0eBu7gHtdCqFt0xJr642LdToM5/cN4Qb9DbHjVx1CP5RyeM+zH7pbecEmDv/lBqb0QH+6Uqq75rxFPkM0w==
+
 stubs@^3.0.0:
   version "3.0.0"
   resolved "https://registry.yarnpkg.com/stubs/-/stubs-3.0.0.tgz#e8d2ba1fa9c90570303c030b6900f7d5f89abe5b"
@@ -15748,6 +15791,13 @@ tweetnacl@^0.14.3, tweetnacl@~0.14.0:
   resolved "https://registry.yarnpkg.com/tweetnacl/-/tweetnacl-0.14.5.tgz#5ae68177f192d4456269d108afa93ff8743f4f64"
   integrity sha1-WuaBd/GS1EViadEIr6k/+HQ/T2Q=
 
+type-check@^0.4.0, type-check@~0.4.0:
+  version "0.4.0"
+  resolved "https://registry.yarnpkg.com/type-check/-/type-check-0.4.0.tgz#07b8203bfa7056c0657050e3ccd2c37730bab8f1"
+  integrity sha512-XleUoc9uwGXqjWwXaUTZAmzMcFZ5858QA2vvx1Ur5xIcixXIP+8LnFDgRplU30us6teqdlskFfu+ae4K79Ooew==
+  dependencies:
+    prelude-ls "^1.2.1"
+
 type-check@~0.3.2:
   version "0.3.2"
   resolved "https://registry.yarnpkg.com/type-check/-/type-check-0.3.2.tgz#5884cab512cf1d355e3fb784f30804b2b520db72"
@@ -16538,7 +16588,7 @@ widest-line@^2.0.0:
   dependencies:
     string-width "^2.1.1"
 
-word-wrap@~1.2.3:
+word-wrap@^1.2.3:
   version "1.2.3"
   resolved "https://registry.yarnpkg.com/word-wrap/-/word-wrap-1.2.3.tgz#610636f6b1f703891bd34771ccb17fb93b47079c"
   integrity sha512-Hz/mrNwitNRh/HUAtM/VT/5VH+ygD6DV7mYKZAtHOrbs8U7lvPS6xf7EJKMF0uW1KJCl0H701g3ZGus+muE5vQ==