Video Wake Lock: wrap optimisation for hidden muted videos around a Feature flag.

Bug: 1086776
Change-Id: I90070ae55c0f6b9ee790ac4df9af1722b75f2489
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2225746
Commit-Queue: Mounir Lamouri <mlamouri@chromium.org>
Reviewed-by: Philip Jägenstedt <foolip@chromium.org>
Cr-Commit-Position: refs/heads/master@{#774864}

content/child/runtime_features.cc

@@ -323,7 +323,8 @@ void SetRuntimeFeaturesFromChromiumFeatures() {
      device::kWebAuthGetAssertionFeaturePolicy, kUseFeatureState},
     {wf::EnableTransformInterop, blink::features::kTransformInterop,
      kUseFeatureState},
-
+    {wf::EnableVideoWakeLockOptimisationHiddenMuted,
+     media::kWakeLockOptimisationHiddenMuted, kUseFeatureState},
   };
   for (const auto& mapping : blinkFeatureToBaseFeatureMapping) {
     SetRuntimeFeatureFromChromiumFeature(

media/base/media_switches.cc

@@ -464,6 +464,9 @@ const base::Feature kFailUrlProvisionFetcherForTesting{
 const base::Feature kHardwareSecureDecryption{
     "HardwareSecureDecryption", base::FEATURE_DISABLED_BY_DEFAULT};
 
+const base::Feature kWakeLockOptimisationHiddenMuted{
+    "kWakeLockOptimisationHiddenMuted", base::FEATURE_ENABLED_BY_DEFAULT};
+
 // Enables encrypted AV1 support in EME requestMediaKeySystemAccess() query by
 // Widevine key system if it is also supported by the underlying Widevine CDM.
 // This feature does not affect the actual playback of encrypted AV1 if it's

media/base/media_switches.h

@@ -171,6 +171,7 @@ MEDIA_EXPORT extern const base::Feature kVaapiLowPowerEncoderGen9x;
 MEDIA_EXPORT extern const base::Feature kVaapiVP8Encoder;
 MEDIA_EXPORT extern const base::Feature kVaapiVP9Encoder;
 MEDIA_EXPORT extern const base::Feature kVideoBlitColorAccuracy;
+MEDIA_EXPORT extern const base::Feature kWakeLockOptimisationHiddenMuted;
 MEDIA_EXPORT extern const base::Feature kWidevineAv1;
 MEDIA_EXPORT extern const base::Feature kWidevineAv1ForceSupportForTesting;
 

third_party/blink/public/platform/web_runtime_features.h

@@ -242,8 +242,9 @@ class WebRuntimeFeatures {
   BLINK_PLATFORM_EXPORT static void EnableTrustTokensAlwaysAllowIssuance(bool);
 
   BLINK_PLATFORM_EXPORT static void EnableInstalledApp(bool);
-
   BLINK_PLATFORM_EXPORT static void EnableTransformInterop(bool);
+  BLINK_PLATFORM_EXPORT static void EnableVideoWakeLockOptimisationHiddenMuted(
+      bool);
 
  private:
   WebRuntimeFeatures();

third_party/blink/renderer/core/html/media/video_wake_lock.cc

@@ -30,7 +30,10 @@ VideoWakeLock::VideoWakeLock(HTMLVideoElement& video)
                                   this, true);
   VideoElement().addEventListener(event_type_names::kVolumechange, this, true);
 
-  StartIntersectionObserver();
+  if (RuntimeEnabledFeatures::VideoWakeLockOptimisationHiddenMutedEnabled())
+    StartIntersectionObserver();
+  else
+    is_visible_ = true;
 
   RemotePlaybackController* remote_playback_controller =
       RemotePlaybackController::From(VideoElement());
@@ -43,8 +46,10 @@ VideoWakeLock::VideoWakeLock(HTMLVideoElement& video)
 void VideoWakeLock::ElementDidMoveToNewDocument() {
   SetExecutionContext(VideoElement().GetExecutionContext());
 
-  intersection_observer_->disconnect();
-  StartIntersectionObserver();
+  if (RuntimeEnabledFeatures::VideoWakeLockOptimisationHiddenMutedEnabled()) {
+    intersection_observer_->disconnect();
+    StartIntersectionObserver();
+  }
 }
 
 void VideoWakeLock::PageVisibilityChanged() {
@@ -53,6 +58,8 @@ void VideoWakeLock::PageVisibilityChanged() {
 
 void VideoWakeLock::OnVisibilityChanged(
     const HeapVector<Member<IntersectionObserverEntry>>& entries) {
+  DCHECK(RuntimeEnabledFeatures::VideoWakeLockOptimisationHiddenMutedEnabled());
+
   is_visible_ = (entries.back()->intersectionRatio() > 0);
   Update();
 }

third_party/blink/renderer/platform/exported/web_runtime_features.cc

@@ -688,4 +688,10 @@ void WebRuntimeFeatures::EnableTransformInterop(bool enable) {
   RuntimeEnabledFeatures::SetTransformInteropEnabled(enable);
 }
 
+void WebRuntimeFeatures::EnableVideoWakeLockOptimisationHiddenMuted(
+    bool enable) {
+  RuntimeEnabledFeatures::SetVideoWakeLockOptimisationHiddenMutedEnabled(
+      enable);
+}
+
 }  // namespace blink

third_party/blink/renderer/platform/runtime_enabled_features.json5

@@ -1860,6 +1860,10 @@
     {
       name: "VideoRotateToFullscreen",
     },
+    {
+      name: "VideoWakeLockOptimisationHiddenMuted",
+      status: "stable",
+    },
     {
       name: "VirtualKeyboard",
       status: "test",