Allow muting/unmuting audio through media track API

media/blink/webmediaplayer_impl.h

Index: media/blink/webmediaplayer_impl.h
diff --git a/media/blink/webmediaplayer_impl.h b/media/blink/webmediaplayer_impl.h
index 027841bd0b266ca91796660d398bcbcfd83c477d..e81e248f28335a63bb68fa12c8aa759b5dc8b499 100644
--- a/media/blink/webmediaplayer_impl.h
+++ b/media/blink/webmediaplayer_impl.h
@@ -127,6 +127,13 @@ class MEDIA_BLINK_EXPORT WebMediaPlayerImpl
   bool hasVideo() const override;
   bool hasAudio() const override;
 
+  void enabledAudioTracksChanged(
+      const blink::WebVector<blink::WebMediaPlayer::TrackId>& enabledTrackIds)
+      override;
+  // |selectedTrackId| is null if no track is selected.
+  void selectedVideoTrackChanged(
+      blink::WebMediaPlayer::TrackId* selectedTrackId) override;
+
   // Dimensions of the video.
   blink::WebSize naturalSize() const override;