Support Widevine in Arm64 Brave on Windows (#18695)

The implementation is described in the new README.md file.

browser/brave_drm_tab_helper.cc

@@ -9,9 +9,9 @@
 #include <vector>
 
 #include "base/containers/contains.h"
-#include "brave/browser/widevine/constants.h"
 #include "brave/browser/widevine/widevine_utils.h"
 #include "brave/components/constants/pref_names.h"
+#include "brave/components/widevine/constants.h"
 #include "build/build_config.h"
 #include "chrome/browser/browser_process_impl.h"
 #include "chrome/browser/profiles/profile.h"

browser/net/BUILD.gn

@@ -89,6 +89,7 @@ source_set("net") {
     "//brave/components/decentralized_dns/content",
     "//brave/components/ipfs/buildflags",
     "//brave/components/update_client:buildflags",
+    "//brave/components/widevine:static_buildflags",
     "//brave/extensions:common",
     "//components/content_settings/core/browser",
     "//components/prefs",

browser/net/brave_static_redirect_network_delegate_helper.cc

@@ -14,6 +14,7 @@
 #include "brave/browser/net/brave_geolocation_buildflags.h"
 #include "brave/browser/safebrowsing/buildflags.h"
 #include "brave/components/constants/network_constants.h"
+#include "brave/components/widevine/static_buildflags.h"
 #include "extensions/common/url_pattern.h"
 #include "net/base/net_errors.h"
 
@@ -87,6 +88,10 @@ int OnBeforeURLRequest_StaticRedirectWorkForGURL(
   static URLPattern widevine_google_dl_pattern(
       URLPattern::SCHEME_HTTP | URLPattern::SCHEME_HTTPS,
       kWidevineGoogleDlPrefix);
+#if BUILDFLAG(WIDEVINE_ARM64_DLL_FIX)
+  static URLPattern widevine_google_dl_pattern_win_arm64(
+      URLPattern::SCHEME_HTTPS, kWidevineGoogleDlPrefixWinArm64);
+#endif  // BUILDFLAG(WIDEVINE_ARM64_DLL_FIX)
 
   if (geo_pattern.MatchesURL(request_url)) {
     *new_url = GURL(BUILDFLAG(GOOGLEAPIS_URL));
@@ -165,6 +170,9 @@ int OnBeforeURLRequest_StaticRedirectWorkForGURL(
   }
 
   if (googleDl_pattern.MatchesURL(request_url) &&
+#if BUILDFLAG(WIDEVINE_ARM64_DLL_FIX)
+      !widevine_google_dl_pattern_win_arm64.MatchesURL(request_url) &&
+#endif
       !widevine_google_dl_pattern.MatchesURL(request_url)) {
     replacements.SetSchemeStr("https");
     replacements.SetHostStr(kBraveRedirectorProxy);

browser/sources.gni

@@ -387,8 +387,8 @@ if (enable_widevine) {
   ]
   brave_chrome_browser_deps += [
     "//brave/browser/widevine",
-    "//brave/browser/widevine:constants",
     "//brave/components/brave_drm",
+    "//brave/components/widevine:constants",
   ]
 }
 

browser/widevine/BUILD.gn

@@ -15,10 +15,10 @@ source_set("widevine") {
   # Remove when https://github.com/brave/brave-browser/issues/10644 is resolved
   check_includes = false
   deps = [
-    ":constants",
     "//base",
     "//brave/app:brave_generated_resources_grit",
     "//brave/components/constants",
+    "//brave/components/widevine:constants",
     "//chrome/common",
     "//components/component_updater/",
     "//components/content_settings/core/common",
@@ -43,10 +43,6 @@ source_set("widevine") {
   ]
 }
 
-source_set("constants") {
-  sources = [ "constants.h" ]
-}
-
 source_set("unittest") {
   testonly = true
 
@@ -67,12 +63,12 @@ source_set("browser_tests") {
   ]
 
   deps = [
-    ":constants",
     ":widevine",
     "//base",
     "//brave/browser",
     "//brave/common",
     "//brave/components/constants",
+    "//brave/components/widevine:constants",
     "//chrome/browser",
     "//chrome/browser:browser_process",
     "//chrome/browser/profiles:profile",

browser/widevine/README.md

@@ -0,0 +1,104 @@
+# Widevine in Brave
+
+Widevine is used to decrypt DRM-protected content, which is served from
+streaming services such as Netflix. Widevine is integrated in Chromium as a
+component.
+
+## Signature files (brave.exe.sig, chrome.dll.sig, ...)
+
+Streaming services only offer high definition content to clients that are
+trusted. Widevine has mechanisms to ensure the integrity of the client. One of
+these mechanisms are .sig files. They prove to Widevine that the browser has not
+been tampered with. In order for Brave's users to see high-definition content,
+the browser must generate and ship with those .sig files.
+
+## Licensing
+
+Brave's licensing agreement for Widevine forbids distribution of Widevine's
+binaries. This entails several workarounds, some of which are listed below.
+
+## Workarounds
+
+### Sequential component updates: SequentialUpdateChecker
+
+Brave has its own components and thus uses its own component update server. This
+server also gets polled by the browser for Widevine. To comply with the
+licensing restriction described above, Brave's component update server responds
+with a redirect to Google's server in this case. This works as long as a single
+update check request only polls for Widevine, and not also for any other
+components. We have a special class, `SequentialUpdateChecker`, that makes sure
+that this is the case.
+
+### Widevine in Arm64 Brave on Windows: WIDEVINE_ARM64_DLL_FIX
+
+As of this writing, Google does not offer Arm64 binaries for Widevine on
+Windows. When Arm64 Brave polls Google's component update server for Widevine,
+then it receives a "noupdate" response, meaning that no version could be found.
+In effect, out of the box, Widevine cannot be installed in Arm64 Brave on
+Windows.
+
+However, there is a workaround: When we poll for an x64 version of the
+component, then we get the necessary base files, plus some x64-specific
+binaries. The remaining necessary binaries for Arm64 are available in a Zip file
+on Google's servers. By placing them into the
+`WidevineCdm\<version>\_platform_specific\win_arm64` directory of the component,
+we can obtain a copy of Widevine that works in Arm64 Brave on Windows.
+
+Brave's `WIDEVINE_ARM64_DLL_FIX` implements the above workaround in code. When
+an update check for Widevine returns "noupdate", then the workaround repeats the
+update check, pretending to be from the `x64` architecture. It installs the x64
+version of the component and then additionally downloads the Arm64 zip file from
+Google's server. This gives us a working copy of Widevine in Arm64 Brave.
+
+The facts that upstream can be compiled for Arm64 on Windows and that Google
+publicly serves Arm64 binaries of Widevine make it seem likely that a native
+Widevine component for this architecture will also be available in the future.
+For this reason, our workaround is guarded by a build flag. Once the workaround
+is no longer required, the build flag makes it very easy to clean up the
+associated code.
+
+**Further details about the present implementation of WIDEVINE_ARM64_DLL_FIX:**
+
+The details below were compiled at the time of the initial implementation, to
+simplify the associated code review. They may be wholly or partially out of
+date by the time you read this.
+
+The first entry point into the implementation is in `update_checker.cc`, in
+`SequentialUpdateChecker::UpdateResultAvailable`. It handles the symptom of the
+current limitation: The browser asks the component update server "Do you have
+the Widevine component?", implicitly sending its architecture, which is Arm64.
+The server responds `"noupdate"`, which means there is no such version. When
+this happens, `UpdateResultAvailable` repeats the update check with a fake
+`x64` architecture.
+
+There is some additional code in `UpdateResultAvailable` that handles the case
+when the server responds `noupdate` not because there is no Arm64 version of
+Widevine at all, but because there is just no _new_ version. If we ever receive
+an Arm64 version of Widevine from the update server, then we disable our
+workaround to not fall back to `x64`. This information is persisted via
+`SequentialUpdateChecker::SetPersistedFlag` and `...:GetPersistedFlag`.
+
+The fake architecture is passed from `update_checker.cc` to
+`protocol_serializer.cc` via the `additional_attributes` parameter of
+`MakeProtocolRequest`.
+
+When the browser receives the response from the update server, it installs the
+Widevine component. Upstream has some custom logic for this in
+`widevine_cdm_component_installer.cc`. We extend this logic to in particular
+overwrite `WidevineCdmComponentInstallerPolicy::OnCustomInstall`. This gets
+called by upstream when the "normal" installation of the component is complete.
+Our additional code downloads and unpacks the external zip file with the
+necessary Arm64 binaries. It also applies some patches to make upstream accept
+the foreign implementation.
+
+To be able to download the Arm64 binaries, the `OnCustomInstall` method
+mentioned above needs a `SharedURLLoaderFactory`. Several sections of our code
+make sure that it receives such an instance in our and upstream's calls of
+`RegisterWidevineCdmComponent`.
+
+Brave intercepts network requests to certain domains for privacy reasons. One
+such domain is `dl.google.com`, which Brave redirects to `redirector.brave.com`.
+Our attempt to download the Zip file with additional Arm64 binaries would
+normally be prevented by this mechanism. We add an exception to
+`brave_static_redirect_network_delegate_helper.cc` so that the Zip file can in
+fact be downloaded.

browser/widevine/widevine_permission_request_browsertest.cc

@@ -7,11 +7,11 @@
 
 #include "base/path_service.h"
 #include "brave/browser/brave_drm_tab_helper.h"
-#include "brave/browser/widevine/constants.h"
 #include "brave/browser/widevine/widevine_permission_request.h"
 #include "brave/browser/widevine/widevine_utils.h"
 #include "brave/components/constants/brave_paths.h"
 #include "brave/components/constants/pref_names.h"
+#include "brave/components/widevine/constants.h"
 #include "build/build_config.h"
 #include "chrome/browser/ssl/cert_verifier_browser_test.h"
 #include "chrome/browser/ui/browser.h"

browser/widevine/widevine_utils.cc

@@ -9,12 +9,14 @@
 #include "base/path_service.h"
 #include "base/task/task_traits.h"
 #include "base/task/thread_pool.h"
-#include "brave/browser/widevine/constants.h"
 #include "brave/browser/widevine/widevine_permission_request.h"
 #include "brave/components/constants/pref_names.h"
+#include "brave/components/widevine/constants.h"
+#include "brave/components/widevine/static_buildflags.h"
 #include "brave/grit/brave_generated_resources.h"
 #include "build/build_config.h"
 #include "chrome/browser/browser_process.h"
+#include "chrome/browser/component_updater/component_updater_utils.h"
 #include "chrome/browser/component_updater/widevine_cdm_component_installer.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/common/chrome_paths.h"
@@ -73,14 +75,22 @@ void ClearWidevinePrefs(Profile* profile) {
   prefs->ClearPref(kWidevineOptedIn);
 }
 
+void InstallWidevineOnceRegistered() {
+  component_updater::BraveOnDemandUpdate(kWidevineComponentId);
+}
+
 }  // namespace
 
 void EnableWidevineCdmComponent() {
   if (IsWidevineOptedIn())
     return;
 
   SetWidevineOptedIn(true);
-  RegisterWidevineCdmComponent(g_browser_process->component_updater());
+  RegisterWidevineCdmComponent(g_browser_process->component_updater(),
+#if BUILDFLAG(WIDEVINE_ARM64_DLL_FIX)
+                               g_browser_process->shared_url_loader_factory(),
+#endif
+                               base::BindOnce(&InstallWidevineOnceRegistered));
 }
 
 void DisableWidevineCdmComponent() {

chromium_src/base/threading/DEPS

@@ -0,0 +1,4 @@
+include_rules = [
+  # This file is NOT generated and is safe to use without a GN dependency.
+  "+brave/components/widevine/static_buildflags.h",
+]

chromium_src/base/threading/thread_restrictions.h

@@ -6,6 +6,8 @@
 #ifndef BRAVE_CHROMIUM_SRC_BASE_THREADING_THREAD_RESTRICTIONS_H_
 #define BRAVE_CHROMIUM_SRC_BASE_THREADING_THREAD_RESTRICTIONS_H_
 
+#include "brave/components/widevine/static_buildflags.h"
+
 class BraveBrowsingDataRemoverDelegate;
 namespace ipfs {
 class IpfsService;
@@ -14,12 +16,32 @@ namespace brave {
 class ProcessLauncher;
 }
 
-#define BRAVE_SCOPED_ALLOW_BASE_SYNC_PRIMITIVES_H  \
-  friend class ::BraveBrowsingDataRemoverDelegate; \
-  friend class ipfs::IpfsService;                  \
+#if BUILDFLAG(WIDEVINE_ARM64_DLL_FIX)
+namespace component_updater {
+class WidevineArm64DllInstaller;
+}
+#endif
+
+#define BRAVE_SCOPED_ALLOW_BASE_SYNC_PRIMITIVES_H_BASE \
+  friend class ::BraveBrowsingDataRemoverDelegate;     \
+  friend class ipfs::IpfsService;                      \
   friend class brave::ProcessLauncher;
 
+#if BUILDFLAG(WIDEVINE_ARM64_DLL_FIX)
+// WidevineArm64DllInstaller needs to use TimedWait:
+#define BRAVE_SCOPED_ALLOW_BASE_SYNC_PRIMITIVES_WIDEVINE_ARM64_DLL_FIX \
+  friend class component_updater::WidevineArm64DllInstaller;
+#else
+#define BRAVE_SCOPED_ALLOW_BASE_SYNC_PRIMITIVES_WIDEVINE_ARM64_DLL_FIX
+#endif
+
+#define BRAVE_SCOPED_ALLOW_BASE_SYNC_PRIMITIVES_H \
+  BRAVE_SCOPED_ALLOW_BASE_SYNC_PRIMITIVES_H_BASE  \
+  BRAVE_SCOPED_ALLOW_BASE_SYNC_PRIMITIVES_WIDEVINE_ARM64_DLL_FIX
+
 #include "src/base/threading/thread_restrictions.h"  // IWYU pragma: export
 #undef BRAVE_SCOPED_ALLOW_BASE_SYNC_PRIMITIVES_H
+#undef BRAVE_SCOPED_ALLOW_BASE_SYNC_PRIMITIVES_H_BASE
+#undef BRAVE_SCOPED_ALLOW_BASE_SYNC_PRIMITIVES_WIDEVINE_ARM64_DLL_FIX
 
 #endif  // BRAVE_CHROMIUM_SRC_BASE_THREADING_THREAD_RESTRICTIONS_H_

chromium_src/chrome/browser/component_updater/DEPS

@@ -0,0 +1,3 @@
+include_rules = [
+  "+brave/components/widevine/static_buildflags.h",
+]

chromium_src/chrome/browser/component_updater/registration.cc

@@ -4,9 +4,22 @@
  * You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "chrome/browser/component_updater/registration.h"
+#include "brave/components/widevine/static_buildflags.h"
+#include "chrome/browser/component_updater/widevine_cdm_component_installer.h"
 
 #define RegisterComponentsForUpdate RegisterComponentsForUpdate_ChromiumImpl
+
+#if BUILDFLAG(WIDEVINE_ARM64_DLL_FIX)
+#define RegisterWidevineCdmComponent(cus) \
+  RegisterWidevineCdmComponent(cus,       \
+                               g_browser_process->shared_url_loader_factory())
+#else
+#define RegisterWidevineCdmComponent(cus) RegisterWidevineCdmComponent(cus)
+#endif
+
 #include "src/chrome/browser/component_updater/registration.cc"
+
+#undef RegisterWidevineCdmComponent
 #undef RegisterComponentsForUpdate
 
 #include "brave/browser/brave_shields/https_everywhere_component_installer.h"