Allow muting/unmuting audio through media track API

media/base/pipeline_impl.h

Index: media/base/pipeline_impl.h
diff --git a/media/base/pipeline_impl.h b/media/base/pipeline_impl.h
index 7a6da3a7b5115974ad31e0ddf7066c0b53b1a4b4..a26b22423224393308a408f9db42977d862af948 100644
--- a/media/base/pipeline_impl.h
+++ b/media/base/pipeline_impl.h
@@ -111,6 +111,10 @@ class MEDIA_EXPORT PipelineImpl : public Pipeline, public DemuxerHost {
   PipelineStatistics GetStatistics() const override;
   void SetCdm(CdmContext* cdm_context,
               const CdmAttachedCB& cdm_attached_cb) override;
+  void OnEnabledAudioStreamsChanged(
+      const std::vector<const DemuxerStream*>& enabledAudioStreams) override;
+  void OnSelectedVideoStreamChanged(
+      const DemuxerStream* selectedVideoStream) override;
 
  private:
   friend class MediaLog;