Allow muting/unmuting audio through media track API

media/blink/webmediaplayer_impl.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef MEDIA_BLINK_WEBMEDIAPLAYER_IMPL_H_
 #define MEDIA_BLINK_WEBMEDIAPLAYER_IMPL_H_
 
 #include <stdint.h>
 
 #include <string>
@@ skipping 109 matching lines @@
   // WebGL texImage2D, ImageBitmap, printing and capturing capabilities.
   void paint(blink::WebCanvas* canvas,
              const blink::WebRect& rect,
              unsigned char alpha,
              SkXfermode::Mode mode) override;
 
   // True if the loaded media has a playable video/audio track.
   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;
 
   // Getters of playback state.
   bool paused() const override;
   bool seeking() const override;
   double duration() const override;
   virtual double timelineOffset() const;
   double currentTime() const override;
 
@@ skipping 349 matching lines @@
   // started; prevents us from spuriously logging errors that are transient or
   // unimportant.
   bool suppress_destruction_errors_;
 
   DISALLOW_COPY_AND_ASSIGN(WebMediaPlayerImpl);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BLINK_WEBMEDIAPLAYER_IMPL_H_