From bd3d9931804b428afa3f6b5d6283e2c2ae0d72eb Mon Sep 17 00:00:00 2001
From: Rob Wu <rob@robwu.nl>
Date: Sun, 1 Sep 2024 01:02:13 +0200
Subject: [PATCH 1/9] [CRX] Use DNR instead of webRequest in preserve-referer

webRequestBlocking is unavailable in MV3. Non-blocking webRequest can
still be used to detect the Referer, but we have to use
declarativeNetRequest to change the Referer header as needed.
---
 extensions/chromium/manifest.json       |   1 +
 extensions/chromium/pdfHandler.js       |   4 -
 extensions/chromium/preserve-referer.js | 153 +++++++++++-------------
 web/chromecom.js                        |   3 +
 4 files changed, 73 insertions(+), 88 deletions(-)

diff --git a/extensions/chromium/manifest.json b/extensions/chromium/manifest.json
index 77c39c7770226..9df4de44fb674 100644
--- a/extensions/chromium/manifest.json
+++ b/extensions/chromium/manifest.json
@@ -10,6 +10,7 @@
     "16": "icon16.png"
   },
   "permissions": [
+    "declarativeNetRequestWithHostAccess",
     "webRequest",
     "webRequestBlocking",
     "<all_urls>",
diff --git a/extensions/chromium/pdfHandler.js b/extensions/chromium/pdfHandler.js
index 7277c852800ff..b993751b0e705 100644
--- a/extensions/chromium/pdfHandler.js
+++ b/extensions/chromium/pdfHandler.js
@@ -13,7 +13,6 @@ 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.
 */
-/* globals saveReferer */
 
 "use strict";
 
@@ -139,9 +138,6 @@ chrome.webRequest.onHeadersReceived.addListener(
 
     var viewerUrl = getViewerURL(details.url);
 
-    // Implemented in preserve-referer.js
-    saveReferer(details);
-
     return { redirectUrl: viewerUrl };
   },
   {
diff --git a/extensions/chromium/preserve-referer.js b/extensions/chromium/preserve-referer.js
index 5e53782b66be2..3bdbff9c69789 100644
--- a/extensions/chromium/preserve-referer.js
+++ b/extensions/chromium/preserve-referer.js
@@ -13,20 +13,14 @@ 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.
 */
-/* globals getHeaderFromHeaders */
-/* exported saveReferer */
 
 "use strict";
 /**
  * This file is one part of the Referer persistency implementation. The other
  * part resides in chromecom.js.
  *
- * This file collects request headers for every http(s) request, and temporarily
- * stores the request headers in a dictionary. Upon completion of the request
- * (success or failure), the headers are discarded.
- * pdfHandler.js will call saveReferer(details) when it is about to redirect to
- * the viewer. Upon calling saveReferer, the Referer header is extracted from
- * the request headers and saved.
+ * This file collects Referer headers for every http(s) request, and temporarily
+ * stores the request headers in a dictionary, for REFERRER_IN_MEMORY_TIME ms.
  *
  * When the viewer is opened, it opens a port ("chromecom-referrer"). This port
  * is used to set up the webRequest listeners that stick the Referer headers to
@@ -36,50 +30,38 @@ limitations under the License.
  * See setReferer in chromecom.js for more explanation of this logic.
  */
 
-// Remembers the request headers for every http(s) page request for the duration
-// of the request.
-var g_requestHeaders = {};
 // g_referrers[tabId][frameId] = referrer of PDF frame.
 var g_referrers = {};
+var g_referrerTimers = {};
+// The background script will eventually suspend after 30 seconds of inactivity.
+// This can be delayed when extension events are firing. To prevent the data
+// from being kept in memory for too long, cap the data duration to 5 minutes.
+var REFERRER_IN_MEMORY_TIME = 300000;
 
-(function () {
-  var requestFilter = {
-    urls: ["*://*/*"],
-    types: ["main_frame", "sub_frame"],
-  };
-  chrome.webRequest.onSendHeaders.addListener(
-    function (details) {
-      g_requestHeaders[details.requestId] = details.requestHeaders;
-    },
-    requestFilter,
-    ["requestHeaders", "extraHeaders"]
-  );
-  chrome.webRequest.onBeforeRedirect.addListener(forgetHeaders, requestFilter);
-  chrome.webRequest.onCompleted.addListener(forgetHeaders, requestFilter);
-  chrome.webRequest.onErrorOccurred.addListener(forgetHeaders, requestFilter);
-  function forgetHeaders(details) {
-    delete g_requestHeaders[details.requestId];
-  }
-})();
+var rIsReferer = /^referer$/i;
+chrome.webRequest.onSendHeaders.addListener(
+  function saveReferer(details) {
+    const { tabId, frameId, requestHeaders } = details;
+    g_referrers[tabId] ??= {};
+    g_referrers[tabId][frameId] = requestHeaders.find(h =>
+      rIsReferer.test(h.name)
+    )?.value;
+    forgetReferrerEventually(tabId);
+  },
+  { urls: ["*://*/*"], types: ["main_frame", "sub_frame"] },
+  ["requestHeaders", "extraHeaders"]
+);
 
-/**
- * @param {object} details - onHeadersReceived event data.
- */
-function saveReferer(details) {
-  var referer =
-    g_requestHeaders[details.requestId] &&
-    getHeaderFromHeaders(g_requestHeaders[details.requestId], "referer");
-  referer = (referer && referer.value) || "";
-  if (!g_referrers[details.tabId]) {
-    g_referrers[details.tabId] = {};
+function forgetReferrerEventually(tabId) {
+  if (g_referrerTimers[tabId]) {
+    clearTimeout(g_referrerTimers[tabId]);
   }
-  g_referrers[details.tabId][details.frameId] = referer;
+  g_referrerTimers[tabId] = setTimeout(() => {
+    delete g_referrers[tabId];
+    delete g_referrerTimers[tabId];
+  }, REFERRER_IN_MEMORY_TIME);
 }
 
-chrome.tabs.onRemoved.addListener(function (tabId) {
-  delete g_referrers[tabId];
-});
-
 // This method binds a webRequest event handler which adds the Referer header
 // to matching PDF resource requests (only if the Referer is non-empty). The
 // handler is removed as soon as the PDF viewer frame is unloaded.
@@ -89,8 +71,11 @@ chrome.runtime.onConnect.addListener(function onReceivePort(port) {
   }
   var tabId = port.sender.tab.id;
   var frameId = port.sender.frameId;
+  var dnrRequestId;
 
   // If the PDF is viewed for the first time, then the referer will be set here.
+  // Note: g_referrers could be empty if the background script was suspended by
+  // the browser. In that case, chromecom.js may send us the referer (below).
   var referer = (g_referrers[tabId] && g_referrers[tabId][frameId]) || "";
   port.onMessage.addListener(function (data) {
     // If the viewer was opened directly (without opening a PDF URL first), then
@@ -99,49 +84,49 @@ chrome.runtime.onConnect.addListener(function onReceivePort(port) {
     if (data.referer) {
       referer = data.referer;
     }
-    chrome.webRequest.onBeforeSendHeaders.removeListener(onBeforeSendHeaders);
-    if (referer) {
-      // Only add a blocking request handler if the referer has to be rewritten.
-      chrome.webRequest.onBeforeSendHeaders.addListener(
-        onBeforeSendHeaders,
-        {
-          urls: [data.requestUrl],
-          types: ["xmlhttprequest"],
-          tabId,
-        },
-        ["blocking", "requestHeaders", "extraHeaders"]
-      );
-    }
-    // Acknowledge the message, and include the latest referer for this frame.
-    port.postMessage(referer);
+    dnrRequestId = data.dnrRequestId;
+    setStickyReferrer(dnrRequestId, tabId, data.requestUrl, referer, () => {
+      // Acknowledge the message, and include the latest referer for this frame.
+      port.postMessage(referer);
+    });
   });
 
   // The port is only disconnected when the other end reloads.
   port.onDisconnect.addListener(function () {
-    if (g_referrers[tabId]) {
-      delete g_referrers[tabId][frameId];
-    }
-    chrome.webRequest.onBeforeSendHeaders.removeListener(onBeforeSendHeaders);
+    unsetStickyReferrer(dnrRequestId);
   });
+});
 
-  function onBeforeSendHeaders(details) {
-    if (details.frameId !== frameId) {
-      return undefined;
-    }
-    var headers = details.requestHeaders;
-    var refererHeader = getHeaderFromHeaders(headers, "referer");
-    if (!refererHeader) {
-      refererHeader = { name: "Referer" };
-      headers.push(refererHeader);
-    } else if (
-      refererHeader.value &&
-      refererHeader.value.lastIndexOf("chrome-extension:", 0) !== 0
-    ) {
-      // Sanity check. If the referer is set, and the value is not the URL of
-      // this extension, then the request was not initiated by this extension.
-      return undefined;
-    }
-    refererHeader.value = referer;
-    return { requestHeaders: headers };
+function setStickyReferrer(dnrRequestId, tabId, url, referer, callback) {
+  if (!referer) {
+    unsetStickyReferrer(dnrRequestId);
+    callback();
+    return;
   }
-});
+  const rule = {
+    id: dnrRequestId,
+    condition: {
+      urlFilter: `|${url}|`,
+      // The viewer and background are presumed to have the same origin:
+      initiatorDomains: [location.hostname], // = chrome.runtime.id.
+      resourceTypes: ["xmlhttprequest"],
+      tabIds: [tabId],
+    },
+    action: {
+      type: "modifyHeaders",
+      requestHeaders: [{ operation: "set", header: "referer", value: referer }],
+    },
+  };
+  chrome.declarativeNetRequest.updateSessionRules(
+    { removeRuleIds: [dnrRequestId], addRules: [rule] },
+    callback
+  );
+}
+
+function unsetStickyReferrer(dnrRequestId) {
+  if (dnrRequestId) {
+    chrome.declarativeNetRequest.updateSessionRules({
+      removeRuleIds: [dnrRequestId],
+    });
+  }
+}
diff --git a/web/chromecom.js b/web/chromecom.js
index cb95a89c2ab11..b41f13bce6bbd 100644
--- a/web/chromecom.js
+++ b/web/chromecom.js
@@ -267,6 +267,7 @@ if (window === top) {
   });
 }
 
+let dnrRequestId;
 // This port is used for several purposes:
 // 1. When disconnected, the background page knows that the frame has unload.
 // 2. When the referrer was saved in history.state.chromecomState, it is sent
@@ -281,6 +282,7 @@ let port;
 // 3. Background -> page: Send latest referer and save to history.
 // 4. Page: Invoke callback.
 function setReferer(url, callback) {
+  dnrRequestId ??= crypto.getRandomValues(new Uint32Array(1))[0] % 0x80000000;
   if (!port) {
     // The background page will accept the port, and keep adding the Referer
     // request header to requests to |url| until the port is disconnected.
@@ -290,6 +292,7 @@ function setReferer(url, callback) {
   port.onMessage.addListener(onMessage);
   // Initiate the information exchange.
   port.postMessage({
+    dnrRequestId,
     referer: window.history.state?.chromecomState,
     requestUrl: url,
   });

From b23829fc60dab77448f30012a575b8368885497d Mon Sep 17 00:00:00 2001
From: Rob Wu <rob@robwu.nl>
Date: Sun, 1 Sep 2024 20:38:47 +0200
Subject: [PATCH 2/9] [CRX] Drop chrome_style from manifest.json

MV3 does not support chrome_style in options_ui. Remove it and replace
it with the minimal amount of styles that still has some spacing around
the individual settings for readability.
---
 extensions/chromium/manifest.json        |  3 +--
 extensions/chromium/options/options.html | 13 +++++++++----
 2 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/extensions/chromium/manifest.json b/extensions/chromium/manifest.json
index 9df4de44fb674..ee9f4e736ee40 100644
--- a/extensions/chromium/manifest.json
+++ b/extensions/chromium/manifest.json
@@ -31,8 +31,7 @@
     "managed_schema": "preferences_schema.json"
   },
   "options_ui": {
-    "page": "options/options.html",
-    "chrome_style": true
+    "page": "options/options.html"
   },
   "options_page": "options/options.html",
   "background": {
diff --git a/extensions/chromium/options/options.html b/extensions/chromium/options/options.html
index 78385926fc98f..bd18c2456465f 100644
--- a/extensions/chromium/options/options.html
+++ b/extensions/chromium/options/options.html
@@ -19,13 +19,19 @@
 <meta charset="utf-8">
 <title>PDF.js viewer options</title>
 <style>
-/* TODO: Remove as much custom CSS as possible - crbug.com/446511 */
 body {
   min-width: 400px; /* a page at the settings page is at least 400px wide */
   margin: 14px 17px; /* already added by default in Chrome 40.0.2212.0 */
 }
 .settings-row {
-  margin: 0.65em 0;
+  margin: 1em 0;
+}
+.checkbox label {
+  display: inline-flex;
+  align-items: center;
+}
+.checkbox label input {
+  flex-shrink: 0;
 }
 </style>
 </head>
@@ -34,8 +40,7 @@
 <button id="reset-button" type="button">Restore default settings</button>
 
 <template id="checkbox-template">
-<!-- Chromium's style: //src/extensions/renderer/resources/extension.css -->
-<div class="checkbox">
+<div class="settings-row checkbox">
   <label>
     <input type="checkbox">
     <span></span>

From 23bc46d51a9afcf1fd63c645b7d1a0808b5a3b35 Mon Sep 17 00:00:00 2001
From: Rob Wu <rob@robwu.nl>
Date: Sun, 1 Sep 2024 21:38:01 +0200
Subject: [PATCH 3/9] [CRX] Replace deprecated extension.getURL with
 runtime.getURL

---
 extensions/chromium/contentscript.js    | 2 +-
 extensions/chromium/extension-router.js | 4 ++--
 extensions/chromium/pdfHandler.js       | 2 +-
 3 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/extensions/chromium/contentscript.js b/extensions/chromium/contentscript.js
index aa6edb7b3f3aa..70fa38701b3c6 100644
--- a/extensions/chromium/contentscript.js
+++ b/extensions/chromium/contentscript.js
@@ -16,7 +16,7 @@ limitations under the License.
 
 "use strict";
 
-var VIEWER_URL = chrome.extension.getURL("content/web/viewer.html");
+var VIEWER_URL = chrome.runtime.getURL("content/web/viewer.html");
 
 function getViewerURL(pdf_url) {
   return VIEWER_URL + "?file=" + encodeURIComponent(pdf_url);
diff --git a/extensions/chromium/extension-router.js b/extensions/chromium/extension-router.js
index a128a30d111e0..bd0cdc875d265 100644
--- a/extensions/chromium/extension-router.js
+++ b/extensions/chromium/extension-router.js
@@ -17,8 +17,8 @@ limitations under the License.
 "use strict";
 
 (function ExtensionRouterClosure() {
-  var VIEWER_URL = chrome.extension.getURL("content/web/viewer.html");
-  var CRX_BASE_URL = chrome.extension.getURL("/");
+  var VIEWER_URL = chrome.runtime.getURL("content/web/viewer.html");
+  var CRX_BASE_URL = chrome.runtime.getURL("/");
 
   var schemes = [
     "http",
diff --git a/extensions/chromium/pdfHandler.js b/extensions/chromium/pdfHandler.js
index b993751b0e705..992ec883c7b85 100644
--- a/extensions/chromium/pdfHandler.js
+++ b/extensions/chromium/pdfHandler.js
@@ -16,7 +16,7 @@ limitations under the License.
 
 "use strict";
 
-var VIEWER_URL = chrome.extension.getURL("content/web/viewer.html");
+var VIEWER_URL = chrome.runtime.getURL("content/web/viewer.html");
 
 function getViewerURL(pdf_url) {
   // |pdf_url| may contain a fragment such as "#page=2". That should be passed

From bc4890d4d4cce1bf8d5ff32c8175dc4a96cf7167 Mon Sep 17 00:00:00 2001
From: Rob Wu <rob@robwu.nl>
Date: Sun, 1 Sep 2024 22:05:06 +0200
Subject: [PATCH 4/9] [CRX] Remove restoretab.js logic

restoretab.js was added in https://github.com/mozilla/pdf.js/pull/6233
with the purpose of restoring lost tabs when Chrome closes all extension
tabs when it reloads the extension. This forced reload can happen when
the user toggles the "Allow access to file URLs" option.

This logic does not work any more, and since the use of localStorage is
a blocker in migrating to MV3, this patch just drops the logic.
---
 extensions/chromium/extension-router.js | 24 -------------------
 extensions/chromium/restoretab.html     | 17 --------------
 extensions/chromium/restoretab.js       | 31 -------------------------
 web/chromecom.js                        | 18 --------------
 4 files changed, 90 deletions(-)
 delete mode 100644 extensions/chromium/restoretab.html
 delete mode 100644 extensions/chromium/restoretab.js

diff --git a/extensions/chromium/extension-router.js b/extensions/chromium/extension-router.js
index bd0cdc875d265..6d64b41ac1742 100644
--- a/extensions/chromium/extension-router.js
+++ b/extensions/chromium/extension-router.js
@@ -100,28 +100,4 @@ limitations under the License.
     }
   );
   console.log("Set up extension URL router.");
-
-  Object.keys(localStorage).forEach(function (key) {
-    // The localStorage item is set upon unload by chromecom.js.
-    var parsedKey = /^unload-(\d+)-(true|false)-(.+)/.exec(key);
-    if (parsedKey) {
-      var timeStart = parseInt(parsedKey[1], 10);
-      var isHidden = parsedKey[2] === "true";
-      var url = parsedKey[3];
-      if (Date.now() - timeStart < 3000) {
-        // Is it a new item (younger than 3 seconds)? Assume that the extension
-        // just reloaded, so restore the tab (work-around for crbug.com/511670).
-        chrome.tabs.create({
-          url:
-            chrome.runtime.getURL("restoretab.html") +
-            "?" +
-            encodeURIComponent(url) +
-            "#" +
-            encodeURIComponent(localStorage.getItem(key)),
-          active: !isHidden,
-        });
-      }
-      localStorage.removeItem(key);
-    }
-  });
 })();
diff --git a/extensions/chromium/restoretab.html b/extensions/chromium/restoretab.html
deleted file mode 100644
index 6e6fa425dd559..0000000000000
--- a/extensions/chromium/restoretab.html
+++ /dev/null
@@ -1,17 +0,0 @@
-<!doctype html>
-<!--
-Copyright 2015 Mozilla Foundation
-
-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.
--->
-<script src="restoretab.js"></script>
diff --git a/extensions/chromium/restoretab.js b/extensions/chromium/restoretab.js
deleted file mode 100644
index 0f1c6c605140e..0000000000000
--- a/extensions/chromium/restoretab.js
+++ /dev/null
@@ -1,31 +0,0 @@
-/*
-Copyright 2015 Mozilla Foundation
-
-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.
-*/
-
-/**
- * This is part of the work-around for crbug.com/511670.
- * - chromecom.js sets the URL and history state upon unload.
- * - extension-router.js retrieves the saved state and opens restoretab.html
- * - restoretab.html (this script) restores the URL and history state.
- */
-"use strict";
-
-var url = decodeURIComponent(location.search.slice(1));
-var historyState = decodeURIComponent(location.hash.slice(1));
-
-historyState = historyState === "undefined" ? null : JSON.parse(historyState);
-
-history.replaceState(historyState, null, url);
-location.reload();
diff --git a/web/chromecom.js b/web/chromecom.js
index b41f13bce6bbd..4f72b2327e0a7 100644
--- a/web/chromecom.js
+++ b/web/chromecom.js
@@ -249,24 +249,6 @@ function requestAccessToLocalFile(fileUrl, overlayManager, callback) {
   });
 }
 
-if (window === top) {
-  // Chrome closes all extension tabs (crbug.com/511670) when the extension
-  // reloads. To counter this, the tab URL and history state is saved to
-  // localStorage and restored by extension-router.js.
-  // Unfortunately, the window and tab index are not restored. And if it was
-  // the only tab in an incognito window, then the tab is not restored either.
-  addEventListener("unload", function () {
-    // If the runtime is still available, the unload is most likely a normal
-    // tab closure. Otherwise it is most likely an extension reload.
-    if (!isRuntimeAvailable()) {
-      localStorage.setItem(
-        "unload-" + Date.now() + "-" + document.hidden + "-" + location.href,
-        JSON.stringify(history.state)
-      );
-    }
-  });
-}
-
 let dnrRequestId;
 // This port is used for several purposes:
 // 1. When disconnected, the background page knows that the frame has unload.

From 7017d8246b9dc72a38f4cfe9b99137bb8a0c6b82 Mon Sep 17 00:00:00 2001
From: Rob Wu <rob@robwu.nl>
Date: Sun, 1 Sep 2024 22:54:49 +0200
Subject: [PATCH 5/9] [CRX] Replace localStorage in telemetry logic

In MV3, the background script is a service worker. localStorage is not
supported in service workers. Switch to storage.local instead.

Data migration is not implemented because it is not needed due to the
privacy-friendly design of the telemetry: In practice the data is reset
about every 4 weeks, when the major version of Chrome is updated.
---
 extensions/chromium/manifest.json |  1 +
 extensions/chromium/telemetry.js  | 45 +++++++++++++++++++++++++++----
 2 files changed, 41 insertions(+), 5 deletions(-)

diff --git a/extensions/chromium/manifest.json b/extensions/chromium/manifest.json
index ee9f4e736ee40..8fd2649c1109e 100644
--- a/extensions/chromium/manifest.json
+++ b/extensions/chromium/manifest.json
@@ -10,6 +10,7 @@
     "16": "icon16.png"
   },
   "permissions": [
+    "alarms",
     "declarativeNetRequestWithHostAccess",
     "webRequest",
     "webRequestBlocking",
diff --git a/extensions/chromium/telemetry.js b/extensions/chromium/telemetry.js
index 7a985e3a186a8..b0cb34ef4a0bd 100644
--- a/extensions/chromium/telemetry.js
+++ b/extensions/chromium/telemetry.js
@@ -42,8 +42,35 @@ limitations under the License.
     return;
   }
 
-  maybeSendPing();
-  setInterval(maybeSendPing, 36e5);
+  // The localStorage API is unavailable in service workers. We store data in
+  // chrome.storage.local and use this "localStorage" object to enable
+  // synchronous access in the logic.
+  const localStorage = {
+    telemetryLastTime: 0,
+    telemetryDeduplicationId: "",
+    telemetryLastVersion: "",
+  };
+
+  chrome.alarms.onAlarm.addListener(alarm => {
+    if (alarm.name === "maybeSendPing") {
+      maybeSendPing();
+    }
+  });
+  chrome.storage.session.get({ didPingCheck: false }, async items => {
+    if (items?.didPingCheck) {
+      return;
+    }
+    maybeSendPing();
+    await chrome.alarms.clear("maybeSendPing");
+    await chrome.alarms.create("maybeSendPing", { periodInMinutes: 60 });
+    chrome.storage.session.set({ didPingCheck: true });
+  });
+
+  function updateLocalStorage(key, value) {
+    localStorage[key] = value;
+    // Note: We mirror the data in localStorage because the following is async.
+    chrome.storage.local.set({ [key]: value });
+  }
 
   function maybeSendPing() {
     getLoggingPref(function (didOptOut) {
@@ -61,12 +88,20 @@ limitations under the License.
         // send more pings.
         return;
       }
+      doSendPing();
+    });
+  }
+
+  function doSendPing() {
+    chrome.storage.local.get(localStorage, items => {
+      Object.assign(localStorage, items);
+
       var lastTime = parseInt(localStorage.telemetryLastTime) || 0;
       var wasUpdated = didUpdateSinceLastCheck();
       if (!wasUpdated && Date.now() - lastTime < MINIMUM_TIME_BETWEEN_PING) {
         return;
       }
-      localStorage.telemetryLastTime = Date.now();
+      updateLocalStorage("telemetryLastTime", Date.now());
 
       var deduplication_id = getDeduplicationId(wasUpdated);
       var extension_version = chrome.runtime.getManifest().version;
@@ -104,7 +139,7 @@ limitations under the License.
       for (const c of buf) {
         id += (c >>> 4).toString(16) + (c & 0xf).toString(16);
       }
-      localStorage.telemetryDeduplicationId = id;
+      updateLocalStorage("telemetryDeduplicationId", id);
     }
     return id;
   }
@@ -119,7 +154,7 @@ limitations under the License.
     if (!chromeVersion || localStorage.telemetryLastVersion === chromeVersion) {
       return false;
     }
-    localStorage.telemetryLastVersion = chromeVersion;
+    updateLocalStorage("telemetryLastVersion", chromeVersion);
     return true;
   }
 

From 3fe256cd0d8f7ac09a683775c2e9df5d35255947 Mon Sep 17 00:00:00 2001
From: Rob Wu <rob@robwu.nl>
Date: Mon, 2 Sep 2024 01:34:25 +0200
Subject: [PATCH 6/9] [CRX] Set manifest_version to 3

- Replace DOM-based pdfHandler.html (background page) with background.js
  (extension service worker).

- Adjust logic of background scripts to account for the fact that the
  scripts can execute repeatedly during a browser session. Primarily,
  register relevant extension event handlers at the top level and use
  in-memory storage.session API to keep track of initialization state.

- Extension URL router: replace blocking webRequest with the service
  worker-specific "fetch" event.

- PDF detection: replace blocking webRequest with declarativeNetRequest.
  This requires Chrome 128+. The next commit will add a fallback for
  earlier Chrome versions.
---
 extensions/chromium/.eslintrc                 |  19 +
 .../{pdfHandler.html => background.js}        |  24 +-
 extensions/chromium/extension-router.js       |  67 +--
 extensions/chromium/manifest.json             |  31 +-
 extensions/chromium/options/migration.js      |  26 +-
 extensions/chromium/pdfHandler.js             | 380 ++++++++++--------
 extensions/chromium/suppress-update.js        |   7 +-
 web/chromecom.js                              |   6 +-
 8 files changed, 329 insertions(+), 231 deletions(-)
 rename extensions/chromium/{pdfHandler.html => background.js} (62%)

diff --git a/extensions/chromium/.eslintrc b/extensions/chromium/.eslintrc
index ba6fdbd4bf4ce..dd74b7b7c64ab 100644
--- a/extensions/chromium/.eslintrc
+++ b/extensions/chromium/.eslintrc
@@ -14,4 +14,23 @@
   "rules": {
     "no-var": "off",
   },
+
+  "overrides": [
+    {
+      // Include all files referenced in background.js
+      "files": [
+        "options/migration.js",
+        "preserve-referer.js",
+        "pdfHandler.js",
+        "extension-router.js",
+        "suppress-update.js",
+        "telemetry.js"
+      ],
+      "env": {
+        // Background script is a service worker.
+        "browser": false,
+        "serviceworker": true
+      }
+    }
+  ]
 }
diff --git a/extensions/chromium/pdfHandler.html b/extensions/chromium/background.js
similarity index 62%
rename from extensions/chromium/pdfHandler.html
rename to extensions/chromium/background.js
index 7a5a036e9c4d5..bb448be549c0c 100644
--- a/extensions/chromium/pdfHandler.html
+++ b/extensions/chromium/background.js
@@ -1,6 +1,5 @@
-<!doctype html>
-<!--
-Copyright 2012 Mozilla Foundation
+/*
+Copyright 2024 Mozilla Foundation
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
@@ -13,10 +12,15 @@
 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.
--->
-<script src="options/migration.js"></script>
-<script src="preserve-referer.js"></script>
-<script src="pdfHandler.js"></script>
-<script src="extension-router.js"></script>
-<script src="suppress-update.js"></script>
-<script src="telemetry.js"></script>
+*/
+
+"use strict";
+
+importScripts(
+  "options/migration.js",
+  "preserve-referer.js",
+  "pdfHandler.js",
+  "extension-router.js",
+  "suppress-update.js",
+  "telemetry.js"
+);
diff --git a/extensions/chromium/extension-router.js b/extensions/chromium/extension-router.js
index 6d64b41ac1742..5bbb0d1a580c7 100644
--- a/extensions/chromium/extension-router.js
+++ b/extensions/chromium/extension-router.js
@@ -55,49 +55,50 @@ limitations under the License.
     return undefined;
   }
 
-  // TODO(rob): Use declarativeWebRequest once declared URL-encoding is
-  //            supported, see http://crbug.com/273589
-  //            (or rewrite the query string parser in viewer.js to get it to
-  //             recognize the non-URL-encoded PDF URL.)
-  chrome.webRequest.onBeforeRequest.addListener(
-    function (details) {
+  function resolveViewerURL(originalUrl) {
+    if (originalUrl.startsWith(CRX_BASE_URL)) {
       // This listener converts chrome-extension://.../http://...pdf to
       // chrome-extension://.../content/web/viewer.html?file=http%3A%2F%2F...pdf
-      var url = parseExtensionURL(details.url);
+      var url = parseExtensionURL(originalUrl);
       if (url) {
         url = VIEWER_URL + "?file=" + url;
-        var i = details.url.indexOf("#");
+        var i = originalUrl.indexOf("#");
         if (i > 0) {
-          url += details.url.slice(i);
+          url += originalUrl.slice(i);
         }
-        console.log("Redirecting " + details.url + " to " + url);
-        return { redirectUrl: url };
+        return url;
       }
-      return undefined;
-    },
-    {
-      types: ["main_frame", "sub_frame"],
-      urls: schemes.map(function (scheme) {
-        // Format: "chrome-extension://[EXTENSIONID]/<scheme>*"
-        return CRX_BASE_URL + scheme + "*";
-      }),
-    },
-    ["blocking"]
-  );
+    }
+    return undefined;
+  }
 
-  // When session restore is used, viewer pages may be loaded before the
-  // webRequest event listener is attached (= page not found).
-  // Or the extension could have been crashed (OOM), leaving a sad tab behind.
-  // Reload these tabs.
-  chrome.tabs.query(
-    {
-      url: CRX_BASE_URL + "*:*",
-    },
-    function (tabsFromLastSession) {
-      for (const { id } of tabsFromLastSession) {
-        chrome.tabs.reload(id);
+  self.addEventListener("fetch", event => {
+    const req = event.request;
+    if (req.destination === "document") {
+      var url = resolveViewerURL(req.url);
+      if (url) {
+        console.log("Redirecting " + req.url + " to " + url);
+        event.respondWith(Response.redirect(url));
       }
     }
+  });
+
+  // Ctrl + F5 bypasses service worker. the pretty extension URLs will fail to
+  // resolve in that case. Catch this and redirect to destination.
+  chrome.webNavigation.onErrorOccurred.addListener(
+    details => {
+      if (details.frameId !== 0) {
+        // Not a top-level frame. Cannot easily navigate a specific child frame.
+        return;
+      }
+      const url = resolveViewerURL(details.url);
+      if (url) {
+        console.log(`Redirecting ${details.url} to ${url} (fallback)`);
+        chrome.tabs.update(details.tabId, { url });
+      }
+    },
+    { url: [{ urlPrefix: CRX_BASE_URL }] }
   );
+
   console.log("Set up extension URL router.");
 })();
diff --git a/extensions/chromium/manifest.json b/extensions/chromium/manifest.json
index 8fd2649c1109e..bcba192967472 100644
--- a/extensions/chromium/manifest.json
+++ b/extensions/chromium/manifest.json
@@ -1,6 +1,6 @@
 {
   "minimum_chrome_version": "88",
-  "manifest_version": 2,
+  "manifest_version": 3,
   "name": "PDF Viewer",
   "version": "PDFJSSCRIPT_VERSION",
   "description": "Uses HTML5 to display PDF files directly in the browser.",
@@ -13,12 +13,11 @@
     "alarms",
     "declarativeNetRequestWithHostAccess",
     "webRequest",
-    "webRequestBlocking",
-    "<all_urls>",
     "tabs",
     "webNavigation",
     "storage"
   ],
+  "host_permissions": ["<all_urls>"],
   "content_scripts": [
     {
       "matches": ["http://*/*", "https://*/*", "file://*/*"],
@@ -36,18 +35,24 @@
   },
   "options_page": "options/options.html",
   "background": {
-    "page": "pdfHandler.html"
+    "service_worker": "background.js"
   },
   "incognito": "split",
   "web_accessible_resources": [
-    "content/web/viewer.html",
-    "http:/*",
-    "https:/*",
-    "file:/*",
-    "chrome-extension:/*",
-    "blob:*",
-    "data:*",
-    "filesystem:/*",
-    "drive:*"
+    {
+      "resources": [
+        "content/web/viewer.html",
+        "http:/*",
+        "https:/*",
+        "file:/*",
+        "chrome-extension:/*",
+        "blob:*",
+        "data:*",
+        "filesystem:/*",
+        "drive:*"
+      ],
+      "matches": ["<all_urls>"],
+      "extension_ids": ["*"]
+    }
   ]
 }
diff --git a/extensions/chromium/options/migration.js b/extensions/chromium/options/migration.js
index dd8fb6ef73d1a..9b084e45ae3f9 100644
--- a/extensions/chromium/options/migration.js
+++ b/extensions/chromium/options/migration.js
@@ -13,10 +13,14 @@ 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.
 */
-/* eslint strict: ["error", "function"] */
+"use strict";
 
-(function () {
-  "use strict";
+chrome.runtime.onInstalled.addListener(({ reason }) => {
+  if (reason !== "update") {
+    // We only need to run migration logic for extension updates, not for new
+    // installs or browser updates.
+    return;
+  }
   var storageLocal = chrome.storage.local;
   var storageSync = chrome.storage.sync;
 
@@ -37,16 +41,12 @@ limitations under the License.
     });
   });
 
-  function getStorageNames(callback) {
-    var x = new XMLHttpRequest();
+  async function getStorageNames(callback) {
     var schema_location = chrome.runtime.getManifest().storage.managed_schema;
-    x.open("get", chrome.runtime.getURL(schema_location));
-    x.onload = function () {
-      var storageKeys = Object.keys(x.response.properties);
-      callback(storageKeys);
-    };
-    x.responseType = "json";
-    x.send();
+    var res = await fetch(chrome.runtime.getURL(schema_location));
+    var storageManifest = await res.json();
+    var storageKeys = Object.keys(storageManifest.properties);
+    callback(storageKeys);
   }
 
   // Save |values| to storage.sync and delete the values with that key from
@@ -150,4 +150,4 @@ limitations under the License.
       }
     );
   }
-})();
+});
diff --git a/extensions/chromium/pdfHandler.js b/extensions/chromium/pdfHandler.js
index 992ec883c7b85..1e1629309e80b 100644
--- a/extensions/chromium/pdfHandler.js
+++ b/extensions/chromium/pdfHandler.js
@@ -18,183 +18,245 @@ limitations under the License.
 
 var VIEWER_URL = chrome.runtime.getURL("content/web/viewer.html");
 
-function getViewerURL(pdf_url) {
-  // |pdf_url| may contain a fragment such as "#page=2". That should be passed
-  // as a fragment to the viewer, not encoded in pdf_url.
-  var hash = "";
-  var i = pdf_url.indexOf("#");
-  if (i > 0) {
-    hash = pdf_url.slice(i);
-    pdf_url = pdf_url.slice(0, i);
-  }
-  return VIEWER_URL + "?file=" + encodeURIComponent(pdf_url) + hash;
-}
-
-/**
- * @param {Object} details First argument of the webRequest.onHeadersReceived
- *                         event. The property "url" is read.
- * @returns {boolean} True if the PDF file should be downloaded.
- */
-function isPdfDownloadable(details) {
-  if (details.url.includes("pdfjs.action=download")) {
-    return true;
+// Use in-memory storage to ensure that the DNR rules have been registered at
+// least once per session. runtime.onInstalled would have been the most fitting
+// event to ensure that, except there are cases where it does not fire when
+// needed. E.g. in incognito mode: https://issues.chromium.org/issues/41029550
+chrome.storage.session.get({ hasPdfRedirector: false }, async items => {
+  if (items?.hasPdfRedirector) {
+    return;
   }
-  // Display the PDF viewer regardless of the Content-Disposition header if the
-  // file is displayed in the main frame, since most often users want to view
-  // a PDF, and servers are often misconfigured.
-  // If the query string contains "=download", do not unconditionally force the
-  // viewer to open the PDF, but first check whether the Content-Disposition
-  // header specifies an attachment. This allows sites like Google Drive to
-  // operate correctly (#6106).
-  if (details.type === "main_frame" && !details.url.includes("=download")) {
-    return false;
+  const rules = await chrome.declarativeNetRequest.getDynamicRules();
+  if (rules.length) {
+    // Dynamic rules persist across extension updates. We don't expect other
+    // dynamic rules, so just remove them all.
+    await chrome.declarativeNetRequest.updateDynamicRules({
+      removeRuleIds: rules.map(r => r.id),
+    });
   }
-  var cdHeader =
-    details.responseHeaders &&
-    getHeaderFromHeaders(details.responseHeaders, "content-disposition");
-  return cdHeader && /^attachment/i.test(cdHeader.value);
-}
+  await registerPdfRedirectRule();
 
-/**
- * Get the header from the list of headers for a given name.
- * @param {Array} headers responseHeaders of webRequest.onHeadersReceived
- * @returns {undefined|{name: string, value: string}} The header, if found.
- */
-function getHeaderFromHeaders(headers, headerName) {
-  for (const header of headers) {
-    if (header.name.toLowerCase() === headerName) {
-      return header;
-    }
-  }
-  return undefined;
-}
+  // Only set the flag in the end, so that we know for sure that all
+  // asynchronous initialization logic has run. If not, then we will run the
+  // logic again at the next background wakeup.
+  chrome.storage.session.set({ hasPdfRedirector: true });
+});
 
 /**
- * Check if the request is a PDF file.
- * @param {Object} details First argument of the webRequest.onHeadersReceived
- *                         event. The properties "responseHeaders" and "url"
- *                         are read.
- * @returns {boolean} True if the resource is a PDF file.
+ * Registers declarativeNetRequest rules to redirect PDF requests to the viewer.
+ * The caller should clear any previously existing dynamic DNR rules.
+ *
+ * The logic here is the declarative version of the runtime logic in the
+ * webRequest.onHeadersReceived implementation at
+ * https://github.com/mozilla/pdf.js/blob/0676ea19cf17023ec8c2d6ad69a859c345c01dc1/extensions/chromium/pdfHandler.js#L34-L152
  */
-function isPdfFile(details) {
-  var header = getHeaderFromHeaders(details.responseHeaders, "content-type");
-  if (header) {
-    var headerValue = header.value.toLowerCase().split(";", 1)[0].trim();
-    if (headerValue === "application/pdf") {
-      return true;
-    }
-    if (headerValue === "application/octet-stream") {
-      if (details.url.toLowerCase().indexOf(".pdf") > 0) {
-        return true;
-      }
-      var cdHeader = getHeaderFromHeaders(
-        details.responseHeaders,
-        "content-disposition"
-      );
-      if (cdHeader && /\.pdf(["']|$)/i.test(cdHeader.value)) {
-        return true;
-      }
-    }
-  }
-  return false;
-}
+async function registerPdfRedirectRule() {
+  // "allow" means to ignore rules (from this extension) with lower priority.
+  const ACTION_IGNORE_OTHER_RULES = { type: "allow" };
 
-/**
- * Takes a set of headers, and set "Content-Disposition: attachment".
- * @param {Object} details First argument of the webRequest.onHeadersReceived
- *                         event. The property "responseHeaders" is read and
- *                         modified if needed.
- * @returns {Object|undefined} The return value for the onHeadersReceived event.
- *                             Object with key "responseHeaders" if the headers
- *                             have been modified, undefined otherwise.
- */
-function getHeadersWithContentDispositionAttachment(details) {
-  var headers = details.responseHeaders;
-  var cdHeader = getHeaderFromHeaders(headers, "content-disposition");
-  if (!cdHeader) {
-    cdHeader = { name: "Content-Disposition" };
-    headers.push(cdHeader);
+  // Redirect to viewer. The rule condition is expected to specify regexFilter
+  // that matches the full request URL.
+  const ACTION_REDIRECT_TO_VIEWER = {
+    type: "redirect",
+    redirect: {
+      // DNR does not support transformations such as encodeURIComponent on the
+      // match, so we just concatenate the URL as is without modifications.
+      // TODO: use "?file=\\0" when DNR supports transformations as proposed at
+      // https://github.com/w3c/webextensions/issues/636#issuecomment-2165978322
+      regexSubstitution: VIEWER_URL + "?DNR:\\0",
+    },
+  };
+
+  // Rules in order of prority (highest priority rule first).
+  // The required "id" fields will be auto-generated later.
+  const addRules = [
+    {
+      // Do not redirect for URLs containing pdfjs.action=download.
+      condition: {
+        urlFilter: "pdfjs.action=download",
+        resourceTypes: ["main_frame", "sub_frame"],
+      },
+      action: ACTION_IGNORE_OTHER_RULES,
+    },
+    {
+      // Redirect local PDF files if isAllowedFileSchemeAccess is true. No-op
+      // otherwise and then handled by webNavigation.onBeforeNavigate below.
+      condition: {
+        regexFilter: "^file://.*\\.pdf$",
+        resourceTypes: ["main_frame", "sub_frame"],
+      },
+      action: ACTION_REDIRECT_TO_VIEWER,
+    },
+    {
+      // Respect the Content-Disposition:attachment header in sub_frame. But:
+      // Display the PDF viewer regardless of the Content-Disposition header if
+      // the file is displayed in the main frame, since most often users want to
+      // view a PDF, and servers are often misconfigured.
+      condition: {
+        urlFilter: "*",
+        resourceTypes: ["sub_frame"], // Note: no main_frame, handled below.
+        responseHeaders: [
+          {
+            header: "content-disposition",
+            values: ["attachment*"],
+          },
+        ],
+      },
+      action: ACTION_IGNORE_OTHER_RULES,
+    },
+    {
+      // If the query string contains "=download", do not unconditionally force
+      // viewer to open the PDF, but first check whether the Content-Disposition
+      // header specifies an attachment. This allows sites like Google Drive to
+      // operate correctly (#6106).
+      condition: {
+        urlFilter: "=download",
+        resourceTypes: ["main_frame"], // No sub_frame, was handled before.
+        responseHeaders: [
+          {
+            header: "content-disposition",
+            values: ["attachment*"],
+          },
+        ],
+      },
+      action: ACTION_IGNORE_OTHER_RULES,
+    },
+    {
+      // Regular http(s) PDF requests.
+      condition: {
+        regexFilter: "^.*$",
+        // The viewer does not have the original request context and issues a
+        // GET request. The original response to POST requests is unavailable.
+        excludedRequestMethods: ["post"],
+        resourceTypes: ["main_frame", "sub_frame"],
+        responseHeaders: [
+          {
+            header: "content-type",
+            values: ["application/pdf", "application/pdf;*"],
+          },
+        ],
+      },
+      action: ACTION_REDIRECT_TO_VIEWER,
+    },
+    {
+      // Wrong MIME-type, but a PDF file according to the file name in the URL.
+      condition: {
+        regexFilter: "^.*\\.pdf\\b.*$",
+        // The viewer does not have the original request context and issues a
+        // GET request. The original response to POST requests is unavailable.
+        excludedRequestMethods: ["post"],
+        resourceTypes: ["main_frame", "sub_frame"],
+        responseHeaders: [
+          {
+            header: "content-type",
+            values: ["application/octet-stream", "application/octet-stream;*"],
+          },
+        ],
+      },
+      action: ACTION_REDIRECT_TO_VIEWER,
+    },
+    {
+      // Wrong MIME-type, but a PDF file according to Content-Disposition.
+      condition: {
+        regexFilter: "^.*$",
+        // The viewer does not have the original request context and issues a
+        // GET request. The original response to POST requests is unavailable.
+        excludedRequestMethods: ["post"],
+        resourceTypes: ["main_frame", "sub_frame"],
+        responseHeaders: [
+          {
+            header: "content-disposition",
+            values: ["*.pdf", '*.pdf"*', "*.pdf'*"],
+          },
+        ],
+        // We only want to match by content-disposition if Content-Type is set
+        // to application/octet-stream. The responseHeaders condition is a
+        // logical OR instead of AND, so to simulate the AND condition we use
+        // the double negation of excludedResponseHeaders + excludedValues.
+        // This matches any request whose content-type header is set and not
+        // "application/octet-stream". It will also match if "content-type" is
+        // not set, but we are okay with that since the browser would usually
+        // try to sniff the MIME type in that case.
+        excludedResponseHeaders: [
+          {
+            header: "content-type",
+            excludedValues: [
+              "application/octet-stream",
+              "application/octet-stream;*",
+            ],
+          },
+        ],
+      },
+      action: ACTION_REDIRECT_TO_VIEWER,
+    },
+  ];
+  for (const [i, rule] of addRules.entries()) {
+    // id must be unique and at least 1, but i starts at 0. So add +1.
+    rule.id = i + 1;
+    rule.priority = addRules.length - i;
   }
-  if (!/^attachment/i.test(cdHeader.value)) {
-    cdHeader.value = "attachment" + cdHeader.value.replace(/^[^;]+/i, "");
-    return { responseHeaders: headers };
+  try {
+    await chrome.declarativeNetRequest.updateDynamicRules({ addRules });
+    // Note: condition.responseHeaders is only supported in Chrome 128+, but
+    // does not trigger errors in Chrome 123 - 127 as explained at:
+    // https://github.com/w3c/webextensions/issues/638#issuecomment-2181124486
+    //
+    // We do not bother with detecting that because we fall back to catching
+    // PDF documents via the content script.
+  } catch (e) {
+    console.error("Failed to register rules to redirect PDF requests.");
+    console.error(e);
   }
-  return undefined;
 }
 
-chrome.webRequest.onHeadersReceived.addListener(
-  function (details) {
-    if (details.method !== "GET") {
-      // Don't intercept POST requests until http://crbug.com/104058 is fixed.
-      return undefined;
-    }
-    if (!isPdfFile(details)) {
-      return undefined;
-    }
-    if (isPdfDownloadable(details)) {
-      // Force download by ensuring that Content-Disposition: attachment is set
-      return getHeadersWithContentDispositionAttachment(details);
-    }
-
-    var viewerUrl = getViewerURL(details.url);
-
-    return { redirectUrl: viewerUrl };
-  },
-  {
-    urls: ["<all_urls>"],
-    types: ["main_frame", "sub_frame"],
-  },
-  ["blocking", "responseHeaders"]
-);
+function getViewerURL(pdf_url) {
+  // |pdf_url| may contain a fragment such as "#page=2". That should be passed
+  // as a fragment to the viewer, not encoded in pdf_url.
+  var hash = "";
+  var i = pdf_url.indexOf("#");
+  if (i > 0) {
+    hash = pdf_url.slice(i);
+    pdf_url = pdf_url.slice(0, i);
+  }
+  return VIEWER_URL + "?file=" + encodeURIComponent(pdf_url) + hash;
+}
 
-chrome.webRequest.onBeforeRequest.addListener(
+// If the user has not granted access to file:-URLs, then declarativeNetRequest
+// will not catch the request. It is still visible through the webNavigation
+// API though, and we can replace the tab with the viewer.
+// The viewer will detect that it has no access to file:-URLs, and prompt the
+// user to activate file permissions.
+chrome.webNavigation.onBeforeNavigate.addListener(
   function (details) {
-    if (isPdfDownloadable(details)) {
-      return undefined;
-    }
-
-    var viewerUrl = getViewerURL(details.url);
-
-    return { redirectUrl: viewerUrl };
-  },
-  {
-    urls: ["file://*/*.pdf", "file://*/*.PDF"],
-    types: ["main_frame", "sub_frame"],
-  },
-  ["blocking"]
-);
+    // Note: pdfjs.action=download is not checked here because that code path
+    // is not reachable for local files through the viewer when we do not have
+    // file:-access.
+    if (details.frameId === 0) {
+      chrome.extension.isAllowedFileSchemeAccess(function (isAllowedAccess) {
+        if (isAllowedAccess) {
+          // Expected to be handled by DNR. Don't do anything.
+          return;
+        }
 
-chrome.extension.isAllowedFileSchemeAccess(function (isAllowedAccess) {
-  if (isAllowedAccess) {
-    return;
-  }
-  // If the user has not granted access to file:-URLs, then the webRequest API
-  // will not catch the request. It is still visible through the webNavigation
-  // API though, and we can replace the tab with the viewer.
-  // The viewer will detect that it has no access to file:-URLs, and prompt the
-  // user to activate file permissions.
-  chrome.webNavigation.onBeforeNavigate.addListener(
-    function (details) {
-      if (details.frameId === 0 && !isPdfDownloadable(details)) {
         chrome.tabs.update(details.tabId, {
           url: getViewerURL(details.url),
         });
-      }
-    },
-    {
-      url: [
-        {
-          urlPrefix: "file://",
-          pathSuffix: ".pdf",
-        },
-        {
-          urlPrefix: "file://",
-          pathSuffix: ".PDF",
-        },
-      ],
+      });
     }
-  );
-});
+  },
+  {
+    url: [
+      {
+        urlPrefix: "file://",
+        pathSuffix: ".pdf",
+      },
+      {
+        urlPrefix: "file://",
+        pathSuffix: ".PDF",
+      },
+    ],
+  }
+);
 
 chrome.runtime.onMessage.addListener(function (message, sender, sendResponse) {
   if (message && message.action === "getParentOrigin") {
diff --git a/extensions/chromium/suppress-update.js b/extensions/chromium/suppress-update.js
index 009651d9ec1e7..f2dfcc3e0985e 100644
--- a/extensions/chromium/suppress-update.js
+++ b/extensions/chromium/suppress-update.js
@@ -20,7 +20,10 @@ limitations under the License.
 // viewer is not displaying any PDF files. Otherwise the tabs would close, which
 // is quite disruptive (crbug.com/511670).
 chrome.runtime.onUpdateAvailable.addListener(function () {
-  if (chrome.extension.getViews({ type: "tab" }).length === 0) {
+  chrome.tabs.query({ url: chrome.runtime.getURL("*") }, tabs => {
+    if (tabs?.length) {
+      return;
+    }
     chrome.runtime.reload();
-  }
+  });
 });
diff --git a/web/chromecom.js b/web/chromecom.js
index 4f72b2327e0a7..1ece304791c1d 100644
--- a/web/chromecom.js
+++ b/web/chromecom.js
@@ -31,7 +31,11 @@ if (typeof PDFJSDev === "undefined" || !PDFJSDev.test("CHROME")) {
   // is rewritten as soon as possible.
   const queryString = document.location.search.slice(1);
   const m = /(^|&)file=([^&]*)/.exec(queryString);
-  const defaultUrl = m ? decodeURIComponent(m[2]) : "";
+  let defaultUrl = m ? decodeURIComponent(m[2]) : "";
+  if (!defaultUrl && queryString.startsWith("DNR:")) {
+    // Redirected via DNR, see registerPdfRedirectRule in pdfHandler.js.
+    defaultUrl = queryString.slice(4);
+  }
 
   // Example: chrome-extension://.../http://example.com/file.pdf
   const humanReadableUrl = "/" + defaultUrl + location.hash;

From 4327502bf3f2e47d44c043ee00e7602414a8ca6d Mon Sep 17 00:00:00 2001
From: Rob Wu <rob@robwu.nl>
Date: Mon, 2 Sep 2024 01:38:02 +0200
Subject: [PATCH 7/9] [CRX] Add fallback PDF detection for Chrome 127-

---
 extensions/chromium/contentscript.js    | 22 +++++++++++++++++++
 extensions/chromium/pdfHandler.js       |  9 +++++++-
 extensions/chromium/preserve-referer.js | 29 ++++++++++++++++++++++++-
 3 files changed, 58 insertions(+), 2 deletions(-)

diff --git a/extensions/chromium/contentscript.js b/extensions/chromium/contentscript.js
index 70fa38701b3c6..6114c708575ef 100644
--- a/extensions/chromium/contentscript.js
+++ b/extensions/chromium/contentscript.js
@@ -23,6 +23,9 @@ function getViewerURL(pdf_url) {
 }
 
 document.addEventListener("animationstart", onAnimationStart, true);
+if (document.contentType === "application/pdf") {
+  chrome.runtime.sendMessage({ action: "canRequestBody" }, maybeRenderPdfDoc);
+}
 
 function onAnimationStart(event) {
   if (event.animationName === "pdfjs-detected-object-or-embed") {
@@ -221,3 +224,22 @@ function getEmbeddedViewerURL(path) {
   path = a.href;
   return getViewerURL(path) + fragment;
 }
+
+function maybeRenderPdfDoc(isNotPOST) {
+  if (!isNotPOST) {
+    // The document was loaded through a POST request, but we cannot access the
+    // original response body, nor safely send a new request to fetch the PDF.
+    // Until #4483 is fixed, POST requests should be ignored.
+    return;
+  }
+
+  // Detected PDF that was not redirected by the declarativeNetRequest rules.
+  // Maybe because this was served without Content-Type and sniffed as PDF.
+  // Or because this is Chrome 127-, which does not support responseHeaders
+  // condition in declarativeNetRequest (DNR), and PDF requests are therefore
+  // not redirected via DNR.
+
+  // In any case, load the viewer.
+  console.log(`Detected PDF via document, opening viewer for ${document.URL}`);
+  location.href = getEmbeddedViewerURL(document.URL);
+}
diff --git a/extensions/chromium/pdfHandler.js b/extensions/chromium/pdfHandler.js
index 1e1629309e80b..0fd71e9f1f4be 100644
--- a/extensions/chromium/pdfHandler.js
+++ b/extensions/chromium/pdfHandler.js
@@ -14,6 +14,8 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
+/* globals canRequestBody */ // From preserve-referer.js
+
 "use strict";
 
 var VIEWER_URL = chrome.runtime.getURL("content/web/viewer.html");
@@ -202,7 +204,7 @@ async function registerPdfRedirectRule() {
     // https://github.com/w3c/webextensions/issues/638#issuecomment-2181124486
     //
     // We do not bother with detecting that because we fall back to catching
-    // PDF documents via the content script.
+    // PDF documents via maybeRenderPdfDoc in contentscript.js.
   } catch (e) {
     console.error("Failed to register rules to redirect PDF requests.");
     console.error(e);
@@ -303,6 +305,11 @@ chrome.runtime.onMessage.addListener(function (message, sender, sendResponse) {
         url,
       });
     }
+    return undefined;
+  }
+  if (message && message.action === "canRequestBody") {
+    sendResponse(canRequestBody(sender.tab.id, sender.frameId));
+    return undefined;
   }
   return undefined;
 });
diff --git a/extensions/chromium/preserve-referer.js b/extensions/chromium/preserve-referer.js
index 3bdbff9c69789..b352dee3645af 100644
--- a/extensions/chromium/preserve-referer.js
+++ b/extensions/chromium/preserve-referer.js
@@ -30,6 +30,8 @@ limitations under the License.
  * See setReferer in chromecom.js for more explanation of this logic.
  */
 
+/* exported canRequestBody */ // Used in pdfHandler.js
+
 // g_referrers[tabId][frameId] = referrer of PDF frame.
 var g_referrers = {};
 var g_referrerTimers = {};
@@ -38,14 +40,18 @@ var g_referrerTimers = {};
 // from being kept in memory for too long, cap the data duration to 5 minutes.
 var REFERRER_IN_MEMORY_TIME = 300000;
 
+// g_postRequests[tabId] = Set of frameId that were loaded via POST.
+var g_postRequests = {};
+
 var rIsReferer = /^referer$/i;
 chrome.webRequest.onSendHeaders.addListener(
   function saveReferer(details) {
-    const { tabId, frameId, requestHeaders } = details;
+    const { tabId, frameId, requestHeaders, method } = details;
     g_referrers[tabId] ??= {};
     g_referrers[tabId][frameId] = requestHeaders.find(h =>
       rIsReferer.test(h.name)
     )?.value;
+    setCanRequestBody(tabId, frameId, method !== "GET");
     forgetReferrerEventually(tabId);
   },
   { urls: ["*://*/*"], types: ["main_frame", "sub_frame"] },
@@ -59,9 +65,30 @@ function forgetReferrerEventually(tabId) {
   g_referrerTimers[tabId] = setTimeout(() => {
     delete g_referrers[tabId];
     delete g_referrerTimers[tabId];
+    delete g_postRequests[tabId];
   }, REFERRER_IN_MEMORY_TIME);
 }
 
+// Keeps track of whether a document in tabId + frameId is loaded through a
+// POST form submission. Although this logic has nothing to do with referrer
+// tracking, it is still here to enable re-use of the webRequest listener above.
+function setCanRequestBody(tabId, frameId, isPOST) {
+  if (isPOST) {
+    g_postRequests[tabId] ??= new Set();
+    g_postRequests[tabId].add(frameId);
+  } else {
+    g_postRequests[tabId]?.delete(frameId);
+  }
+}
+
+function canRequestBody(tabId, frameId) {
+  // Returns true unless the frame is known to be loaded through a POST request.
+  // If the background suspends, the information may be lost. This is acceptable
+  // because the information is only potentially needed shortly after document
+  // load, by contentscript.js.
+  return !g_postRequests[tabId]?.has(frameId);
+}
+
 // This method binds a webRequest event handler which adds the Referer header
 // to matching PDF resource requests (only if the Referer is non-empty). The
 // handler is removed as soon as the PDF viewer frame is unloaded.

From b3a0ad09ada95b4fa8497eb510d43e4bace64a60 Mon Sep 17 00:00:00 2001
From: Rob Wu <rob@robwu.nl>
Date: Mon, 2 Sep 2024 03:47:25 +0200
Subject: [PATCH 8/9] [CRX] Add work-around for Chrome crash

---
 extensions/chromium/contentscript.js | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/extensions/chromium/contentscript.js b/extensions/chromium/contentscript.js
index 6114c708575ef..83ebf96a225c7 100644
--- a/extensions/chromium/contentscript.js
+++ b/extensions/chromium/contentscript.js
@@ -241,5 +241,21 @@ function maybeRenderPdfDoc(isNotPOST) {
 
   // In any case, load the viewer.
   console.log(`Detected PDF via document, opening viewer for ${document.URL}`);
-  location.href = getEmbeddedViewerURL(document.URL);
+
+  // Ideally we would use logic consistent with the DNR logic, like this:
+  // location.href = getEmbeddedViewerURL(document.URL);
+  // ... unfortunately, this causes Chrome to crash until version 129, fixed by
+  // https://chromium.googlesource.com/chromium/src/+/8c42358b2cc549553d939efe7d36515d80563da7%5E%21/
+  // Work around this by replacing the body with an iframe of the viewer.
+  // Interestingly, Chrome's built-in PDF viewer uses a similar technique.
+  const shadowRoot = document.body.attachShadow({ mode: "closed" });
+  const iframe = document.createElement("iframe");
+  iframe.style.position = "absolute";
+  iframe.style.top = "0";
+  iframe.style.left = "0";
+  iframe.style.width = "100%";
+  iframe.style.height = "100%";
+  iframe.style.border = "0 none";
+  iframe.src = getEmbeddedViewerURL(document.URL);
+  shadowRoot.append(iframe);
 }

From 4bf7be64279a153b2f69d2112fea9cb1b2bbf29e Mon Sep 17 00:00:00 2001
From: Rob Wu <rob@robwu.nl>
Date: Mon, 2 Sep 2024 04:07:56 +0200
Subject: [PATCH 9/9] [CRX] Bump minimum_chrome_version from 88 to 103

The minimum required version is Chrome 103 because wildcard support for
web_accessible_resources[].extension_id was introduced in 103, in
https://chromium.googlesource.com/chromium/src/+/c9caeb1a080f165f48d2a90559aa35d22965b440

A way to broaden compatibility is to drop that key. By doing so, the
minimum required Chrome version is then 96, because of the
chrome.storage.session API (and declarativeNetRequestWithHostAccess).

Since gulpfile.js already defines "Chrome >= 98" and there is no real
point in expanding support to older versions, I'm just setting the
minimum version to 103.
---
 extensions/chromium/manifest.json | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/extensions/chromium/manifest.json b/extensions/chromium/manifest.json
index bcba192967472..27be0ea96ac9f 100644
--- a/extensions/chromium/manifest.json
+++ b/extensions/chromium/manifest.json
@@ -1,5 +1,5 @@
 {
-  "minimum_chrome_version": "88",
+  "minimum_chrome_version": "103",
   "manifest_version": 3,
   "name": "PDF Viewer",
   "version": "PDFJSSCRIPT_VERSION",