start/stop the source of the capturer when 1st audiotrack/last audiotrack is added/removed

content/renderer/media/mock_media_stream_dependency_factory.h

Index: content/renderer/media/mock_media_stream_dependency_factory.h
diff --git a/content/renderer/media/mock_media_stream_dependency_factory.h b/content/renderer/media/mock_media_stream_dependency_factory.h
index 9ed1a1a8f06358597fa0cdd213065d8c0307cf36..65faa6618656236eb73b92058a38b73c748d2ed9 100644
--- a/content/renderer/media/mock_media_stream_dependency_factory.h
+++ b/content/renderer/media/mock_media_stream_dependency_factory.h
@@ -106,34 +106,6 @@ class MockLocalVideoTrack : public webrtc::VideoTrackInterface {
   webrtc::ObserverInterface* observer_;
 };
 
-class MockLocalAudioTrack : public webrtc::AudioTrackInterface {
- public:
-  explicit MockLocalAudioTrack(const std::string& id)
-    : enabled_(false),
-      id_(id),
-      state_(MediaStreamTrackInterface::kLive),
-      observer_(NULL) {
-  }
-  virtual std::string kind() const OVERRIDE;
-  virtual std::string id() const OVERRIDE;
-  virtual bool enabled() const OVERRIDE;
-  virtual TrackState state() const OVERRIDE;
-  virtual bool set_enabled(bool enable) OVERRIDE;
-  virtual bool set_state(TrackState new_state) OVERRIDE;
-  virtual void RegisterObserver(webrtc::ObserverInterface* observer) OVERRIDE;
-  virtual void UnregisterObserver(webrtc::ObserverInterface* observer) OVERRIDE;
-  virtual webrtc::AudioSourceInterface* GetSource() const OVERRIDE;
-
- protected:
-  virtual ~MockLocalAudioTrack() {}
-
- private:
-  bool enabled_;
-  std::string id_;
-  TrackState state_;
-  webrtc::ObserverInterface* observer_;
-};
-
 // A mock factory for creating different objects for
 // RTC MediaStreams and PeerConnections.
 class MockMediaStreamDependencyFactory : public MediaStreamDependencyFactory {