Remove NewAudioRenderingMixingStrategy feature and flag.

Does not remove/change any code except for the simple decision logic that's using the feature.

Bug: 870836
Change-Id: If6f0bc54954cc1d95c6be4f4a1426e51327cefad
Reviewed-on: https://chromium-review.googlesource.com/c/1350909Reviewed-by: Olga Sharonova <olka@chromium.org>
Reviewed-by: Dale Curtis <dalecurtis@chromium.org>
Commit-Queue: Henrik Grunell <grunell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#611347}

chrome/browser/about_flags.cc

@@ -2848,11 +2848,6 @@ const FeatureEntry kFeatureEntries[] = {
     {"fill-on-account-select", flag_descriptions::kFillOnAccountSelectName,
      flag_descriptions::kFillOnAccountSelectDescription, kOsAll,
      FEATURE_VALUE_TYPE(password_manager::features::kFillOnAccountSelect)},
-    {"new-audio-rendering-mixing-strategy",
-     flag_descriptions::kNewAudioRenderingMixingStrategyName,
-     flag_descriptions::kNewAudioRenderingMixingStrategyDescription,
-     kOsWin | kOsMac | kOsLinux | kOsAndroid,
-     FEATURE_VALUE_TYPE(media::kNewAudioRenderingMixingStrategy)},
     {"enable-new-remote-playback-pipeline",
      flag_descriptions::kNewRemotePlaybackPipelineName,
      flag_descriptions::kNewRemotePlaybackPipelineDescription, kOsAll,

content/renderer/media/audio/audio_device_factory.cc

@@ -56,13 +56,10 @@ scoped_refptr<media::AudioOutputDevice> NewOutputDevice(
 }
 
 // This is where we decide which audio will go to mixers and which one to
-// AudioOutpuDevice directly.
+// AudioOutputDevice directly.
 bool IsMixable(AudioDeviceFactory::SourceType source_type) {
-  if (source_type == AudioDeviceFactory::kSourceMediaElement)
-    return true;  // Must ALWAYS go through mixer.
-
-  // Mix everything if experiment is enabled; otherwise mix nothing else.
-  return base::FeatureList::IsEnabled(media::kNewAudioRenderingMixingStrategy);
+  // Media element must ALWAYS go through mixer.
+  return source_type == AudioDeviceFactory::kSourceMediaElement;
 }
 
 scoped_refptr<media::SwitchableAudioRendererSink> NewMixableSink(

media/base/media_switches.cc

@@ -195,10 +195,6 @@ const char kUserGestureRequiredForCrossOriginPolicy[] =
 
 namespace media {
 
-// Use new audio rendering mixer.
-const base::Feature kNewAudioRenderingMixingStrategy{
-    "NewAudioRenderingMixingStrategy", base::FEATURE_DISABLED_BY_DEFAULT};
-
 // Only used for disabling overlay fullscreen (aka SurfaceView) in Clank.
 const base::Feature kOverlayFullscreenVideo{"overlay-fullscreen-video",
                                             base::FEATURE_ENABLED_BY_DEFAULT};

media/base/media_switches.h

@@ -117,7 +117,6 @@ MEDIA_EXPORT extern const base::Feature kMediaEngagementBypassAutoplayPolicies;
 MEDIA_EXPORT extern const base::Feature kMemoryPressureBasedSourceBufferGC;
 MEDIA_EXPORT extern const base::Feature kMojoVideoDecoder;
 MEDIA_EXPORT extern const base::Feature kMseBufferByPts;
-MEDIA_EXPORT extern const base::Feature kNewAudioRenderingMixingStrategy;
 MEDIA_EXPORT extern const base::Feature kNewEncodeCpuLoadEstimator;
 MEDIA_EXPORT extern const base::Feature kNewRemotePlaybackPipeline;
 MEDIA_EXPORT extern const base::Feature kOverflowIconsForMediaControls;