Added a callback function OnAddTrack to PeerConnectionObserver

webrtc/api/peerconnection.cc

 /*
  *  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 1402 matching lines @@
     }
     default:
       RTC_DCHECK(false && "Not implemented");
       break;
   }
 }
 
 void PeerConnection::CreateAudioReceiver(MediaStreamInterface* stream,
                                          const std::string& track_id,
                                          uint32_t ssrc) {
-  receivers_.push_back(
-      RtpReceiverProxyWithInternal<RtpReceiverInternal>::Create(
+  rtc::scoped_refptr<RtpReceiverProxyWithInternal<RtpReceiverInternal>>
+      receiver = RtpReceiverProxyWithInternal<RtpReceiverInternal>::Create(
           signaling_thread(), new AudioRtpReceiver(stream, track_id, ssrc,
-                                                   session_->voice_channel())));
+                                                   session_->voice_channel()));
+
+  receivers_.push_back(receiver);
+  std::vector<rtc::scoped_refptr<MediaStreamInterface>> streams;
+  streams.push_back(rtc::scoped_refptr<MediaStreamInterface>(stream));

[honghaiz3, 2016/11/17 01:19:02]

Is there any reason to use a vector of streams here?

[Zhi Huang, 2016/11/17 01:42:06]

According to the spec: https://www.w3.org/TR/webrtc/#dom-rtctrackevent
the event has a sequence of MediaStream. I think this means a track can be
attached to multiple streams. We may call this OnAddTrack() function once we
encounter that case.

[Taylor Brandstetter, 2016/11/17 02:07:25]

I agree about this. Even if we take a long time to support multiple streams for
one track (or never support it), we might as well be forward thinking so we
don't need to change the callback later.

+  observer_->OnAddTrack(receiver, streams);

[honghaiz3, 2016/11/17 01:52:31]

Should we just get the track from the receiver and use that as the argument?
Something like observer_->OnAddTrack(receiver->track(), stream)?

 }
 
 void PeerConnection::CreateVideoReceiver(MediaStreamInterface* stream,
                                          const std::string& track_id,
                                          uint32_t ssrc) {
-  receivers_.push_back(
-      RtpReceiverProxyWithInternal<RtpReceiverInternal>::Create(
+  rtc::scoped_refptr<RtpReceiverProxyWithInternal<RtpReceiverInternal>>
+      receiver = RtpReceiverProxyWithInternal<RtpReceiverInternal>::Create(
           signaling_thread(),
           new VideoRtpReceiver(stream, track_id, factory_->worker_thread(),
-                               ssrc, session_->video_channel())));
+                               ssrc, session_->video_channel()));
+  receivers_.push_back(receiver);
+  std::vector<rtc::scoped_refptr<MediaStreamInterface>> streams;
+  streams.push_back(rtc::scoped_refptr<MediaStreamInterface>(stream));
+  observer_->OnAddTrack(receiver, streams);
 }
 
 // TODO(deadbeef): Keep RtpReceivers around even if track goes away in remote
 // description.
 void PeerConnection::DestroyReceiver(const std::string& track_id) {
   auto it = FindReceiverForTrack(track_id);
   if (it == receivers_.end()) {
     LOG(LS_WARNING) << "RtpReceiver for track with id " << track_id
                     << " doesn't exist.";
   } else {
@@ skipping 903 matching lines @@
 
 bool PeerConnection::StartRtcEventLog_w(rtc::PlatformFile file,
                                         int64_t max_size_bytes) {
   return event_log_->StartLogging(file, max_size_bytes);
 }
 
 void PeerConnection::StopRtcEventLog_w() {
   event_log_->StopLogging();
 }
 }  // namespace webrtc