RTCMediaStreamTrackStats.ssrcIds collected by RTCStatsCollector.

webrtc/api/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 75 matching lines @@
 
   virtual WebRtcSession* session() { return session_.get(); }
 
   rtc::scoped_refptr<DtmfSenderInterface> CreateDtmfSender(
       AudioTrackInterface* track) override;
 
   rtc::scoped_refptr<RtpSenderInterface> CreateSender(
       const std::string& kind,
       const std::string& stream_id) override;
 
-  std::vector<rtc::scoped_refptr<RtpSenderInterface>> GetSenders()
+  // Virtual for unit tests.
+  virtual std::vector<rtc::scoped_refptr<RtpSenderInterface>> GetSenders()

[Taylor Brandstetter, 2017/01/04 00:36:55]

These are already virtual (hence "override" at the end).

       const override;
-  std::vector<rtc::scoped_refptr<RtpReceiverInterface>> GetReceivers()
+  virtual std::vector<rtc::scoped_refptr<RtpReceiverInterface>> GetReceivers()
       const override;
 
   rtc::scoped_refptr<DataChannelInterface> CreateDataChannel(
       const std::string& label,
       const DataChannelInit* config) override;
   bool GetStats(StatsObserver* observer,
                 webrtc::MediaStreamTrackInterface* track,
                 StatsOutputLevel level) override;
   void GetStats(RTCStatsCollectorCallback* callback) override;
 
@@ skipping 325 matching lines @@
       rtc::scoped_refptr<RtpReceiverProxyWithInternal<RtpReceiverInternal>>>
       receivers_;
   std::unique_ptr<WebRtcSession> session_;
   std::unique_ptr<StatsCollector> stats_;
   rtc::scoped_refptr<RTCStatsCollector> stats_collector_;
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_API_PEERCONNECTION_H_