When a track is added/removed directly to MediaStream notify observer->OnRenegotionNeeded

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 175 matching lines @@
   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 DestroyAudioSender(MediaStreamInterface* stream,
-                          AudioTrackInterface* audio_track,
-                          uint32_t ssrc);
-  void DestroyVideoSender(MediaStreamInterface* stream,
-                          VideoTrackInterface* video_track);
+
+  // 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);
 
   // Implements IceObserver
   void OnIceConnectionStateChange(IceConnectionState new_state) override;
   void OnIceGatheringChange(IceGatheringState new_state) override;
   void OnIceCandidate(
       std::unique_ptr<IceCandidateInterface> candidate) override;
   void OnIceCandidatesRemoved(
       const std::vector<cricket::Candidate>& candidates) override;
   void OnIceConnectionReceivingChange(bool receiving) override;
 
@@ skipping 236 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_