RTCMediaStream[Track]Stats added.

webrtc/api/rtcstatscollector.h

Index: webrtc/api/rtcstatscollector.h
diff --git a/webrtc/api/rtcstatscollector.h b/webrtc/api/rtcstatscollector.h
index 2c160ee414025ccfb0e9e936a1b7c88c3e4d5e04..ae4ba19abc13bfe41099e87a7b73678a6b6f6150 100644
--- a/webrtc/api/rtcstatscollector.h
+++ b/webrtc/api/rtcstatscollector.h
@@ -98,6 +98,9 @@ class RTCStatsCollector : public virtual rtc::RefCountInterface {
   void ProduceIceCandidateAndPairStats_s(
       int64_t timestamp_us, const SessionStats& session_stats,
       RTCStatsReport* report) const;
+  // Produces |RTCMediaStreamStats| and |RTCMediaStreamTrackStats|.
+  void ProduceMediaStreamAndTrackStats_s(
+      int64_t timestamp_us, RTCStatsReport* report) const;
   // Produces |RTCPeerConnectionStats|.
   void ProducePeerConnectionStats_s(
       int64_t timestamp_us, RTCStatsReport* report) const;