Added a callback function OnAddTrack to PeerConnectionObserver

webrtc/api/peerconnectionfactory_unittest.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 68 matching lines @@
   virtual void OnRemoveStream(rtc::scoped_refptr<MediaStreamInterface> stream) {
   }
   virtual void OnDataChannel(
       rtc::scoped_refptr<DataChannelInterface> data_channel) {}
   virtual void OnRenegotiationNeeded() {}
   virtual void OnIceConnectionChange(
       PeerConnectionInterface::IceConnectionState new_state) {}
   virtual void OnIceGatheringChange(
       PeerConnectionInterface::IceGatheringState new_state) {}
   virtual void OnIceCandidate(const webrtc::IceCandidateInterface* candidate) {}
+  virtual void OnAddTrack(
+      rtc::scoped_refptr<webrtc::RtpReceiverInterface> receiver,

[Taylor Brandstetter, 2016/11/17 00:34:23]

Good idea putting just the receiver in the event, since you can get the track
from the receiver.

+      std::vector<rtc::scoped_refptr<MediaStreamInterface>> streams) {}
 };
 
 }  // namespace
 
 class PeerConnectionFactoryTest : public testing::Test {
   void SetUp() {
 #ifdef WEBRTC_ANDROID
     webrtc::InitializeAndroidObjects();
 #endif
     factory_ = webrtc::CreatePeerConnectionFactory(
@@ skipping 255 matching lines @@
   track->set_enabled(false);
   EXPECT_TRUE(capturer->CaptureFrame());
   EXPECT_EQ(2, local_renderer.num_rendered_frames());
   EXPECT_TRUE(local_renderer.black_frame());
 
   track->set_enabled(true);
   EXPECT_TRUE(capturer->CaptureFrame());
   EXPECT_EQ(3, local_renderer.num_rendered_frames());
   EXPECT_FALSE(local_renderer.black_frame());
 }