Revert of MediaStream audio object graph untangling and clean-ups.

content/renderer/media/media_stream_audio_track.h

Index: content/renderer/media/media_stream_audio_track.h
diff --git a/content/renderer/media/media_stream_audio_track.h b/content/renderer/media/media_stream_audio_track.h
index 0ef126b431a3af9bcdc0686f71ecd95a474214bc..2175b4e186f47fefc982e097a1691dac1fdd7383 100644
--- a/content/renderer/media/media_stream_audio_track.h
+++ b/content/renderer/media/media_stream_audio_track.h
@@ -5,7 +5,6 @@
 #ifndef CONTENT_RENDERER_MEDIA_MEDIA_STREAM_AUDIO_TRACK_H_
 #define CONTENT_RENDERER_MEDIA_MEDIA_STREAM_AUDIO_TRACK_H_
 
-#include "base/callback.h"
 #include "base/macros.h"
 #include "content/renderer/media/media_stream_track.h"
 
@@ -17,21 +16,13 @@
 
 class MediaStreamAudioSink;
 
-// TODO(miu): In a soon-upcoming set of refactoring changes, this class will
-// take on the functionality of managing sink connections and the audio data
-// flow between source and sinks.  The WebRTC-specific elements will then be
-// moved into a subclass.   http://crbug.com/577874
 class CONTENT_EXPORT MediaStreamAudioTrack : public MediaStreamTrack {
  public:
   explicit MediaStreamAudioTrack(bool is_local_track);
-
-  // Subclasses must ensure the track is stopped (i.e., Stop() has been called
-  // at least once) before this destructor is invoked.
   ~MediaStreamAudioTrack() override;
 
-  // Returns the MediaStreamAudioTrack instance owned by the given blink |track|
-  // or null.
-  static MediaStreamAudioTrack* From(const blink::WebMediaStreamTrack& track);
+  static MediaStreamAudioTrack* GetTrack(
+      const blink::WebMediaStreamTrack& track);
 
   // Add a sink to the track. This function will trigger a OnSetFormat()
   // call on the |sink|.
@@ -43,7 +34,6 @@
   virtual void RemoveSink(MediaStreamAudioSink* sink) = 0;
 
   // TODO(tommi, xians): Remove this method.
-  // TODO(miu): See class-level TODO comment.  ;-)
   virtual webrtc::AudioTrackInterface* GetAudioAdapter();
 
   // Returns the output format of the capture source. May return an invalid
@@ -54,23 +44,7 @@
   // to the complexity of all types of audio tracks+source implementations.
   virtual media::AudioParameters GetOutputFormat() const = 0;
 
-  // Called to notify this track that the flow of audio data has started from
-  // the source.  |stop_callback| is run by Stop() when the source must halt the
-  // flow of audio data to this track.
-  void Start(const base::Closure& stop_callback);
-
-  // Halts the flow of audio data from the source (and to the sinks), and then
-  // invokes OnStop() to perform any additional actions.
-  void Stop() final;
-
- protected:
-  // Called by Stop() after the source has halted the flow of audio data.
-  virtual void OnStop();
-
  private:
-  // Callback provided to Start() which is run when the audio flow must halt.
-  base::Closure stop_callback_;
-
   DISALLOW_COPY_AND_ASSIGN(MediaStreamAudioTrack);
 };