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 25a1e72ba7e946227ca38b17fbe11d5639e64517..47ae95463d462b69e7e4dace292cbe9c5242d7f5 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;