MediaStream audio: Refactor 3 separate "glue" implementations into one.

content/renderer/media/media_stream_center.h

 // Copyright (c) 2012 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 CONTENT_RENDERER_MEDIA_MEDIA_STREAM_CENTER_H_
 #define CONTENT_RENDERER_MEDIA_MEDIA_STREAM_CENTER_H_
 
 #include <map>
 
 #include "base/compiler_specific.h"
@@ skipping 10 matching lines @@
 class WebAudioSourceProvider;
 class WebMediaStreamCenterClient;
 }
 
 namespace content {
 class PeerConnectionDependencyFactory;
 
 class CONTENT_EXPORT MediaStreamCenter
     : NON_EXPORTED_BASE(public blink::WebMediaStreamCenter) {
  public:
+  // TODO(miu): Remove these constructor args.  They are no longer used.
+  // http://crbug.com/577874
   MediaStreamCenter(blink::WebMediaStreamCenterClient* client,
                     PeerConnectionDependencyFactory* factory);
   ~MediaStreamCenter() override;
 
  private:
   void didCreateMediaStreamTrack(
       const blink::WebMediaStreamTrack& track) override;
 
   void didEnableMediaStreamTrack(
       const blink::WebMediaStreamTrack& track) override;
@@ skipping 11 matching lines @@
 
   void didCreateMediaStream(blink::WebMediaStream& stream) override;
 
   bool didAddMediaStreamTrack(const blink::WebMediaStream& stream,
                               const blink::WebMediaStreamTrack& track) override;
 
   bool didRemoveMediaStreamTrack(
       const blink::WebMediaStream& stream,
       const blink::WebMediaStreamTrack& track) override;
 
-  // |rtc_factory_| is a weak pointer and is owned by the RenderThreadImpl.
-  // It is valid as long as  RenderThreadImpl exist.
-  PeerConnectionDependencyFactory* rtc_factory_;
-
   DISALLOW_COPY_AND_ASSIGN(MediaStreamCenter);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_MEDIA_MEDIA_STREAM_CENTER_H_