Add PeerConnectionObserver::OnRemoveTrack callback.

webrtc/pc/peerconnection.h

 /*
  *  Copyright 2012 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 174 matching lines @@
   // Implements MessageHandler.
   void OnMessage(rtc::Message* msg) override;
 
   void CreateAudioReceiver(MediaStreamInterface* stream,
                            const std::string& track_id,
                            uint32_t ssrc);
 
   void CreateVideoReceiver(MediaStreamInterface* stream,
                            const std::string& track_id,
                            uint32_t ssrc);
-  void DestroyReceiver(const std::string& track_id);
+  void DestroyReceiver(MediaStreamInterface* stream,
+                           const std::string& track_id);
 
   // May be called either by AddStream/RemoveStream, or when a track is
   // added/removed from a stream previously added via AddStream.
   void AddAudioTrack(AudioTrackInterface* track, MediaStreamInterface* stream);
   void RemoveAudioTrack(AudioTrackInterface* track,
                         MediaStreamInterface* stream);
   void AddVideoTrack(VideoTrackInterface* track, MediaStreamInterface* stream);
   void RemoveVideoTrack(VideoTrackInterface* track,
                         MediaStreamInterface* stream);
 
@@ skipping 251 matching lines @@
   std::vector<rtc::scoped_refptr<RtpSenderProxyWithInternal<RtpSenderInternal>>>
       senders_;
   std::vector<
       rtc::scoped_refptr<RtpReceiverProxyWithInternal<RtpReceiverInternal>>>
       receivers_;
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_PC_PEERCONNECTION_H_