RTC[In/Out]boundRTPStreamStats.mediaTrackId collected.

webrtc/api/trackmediainfomap.h

Index: webrtc/api/trackmediainfomap.h
diff --git a/webrtc/api/trackmediainfomap.h b/webrtc/api/trackmediainfomap.h
index a61357e9418c753b13ffc2740ef38dd64ea252f1..7e1b405d8d70b5f4347c30f705923227bfdbc490 100644
--- a/webrtc/api/trackmediainfomap.h
+++ b/webrtc/api/trackmediainfomap.h
@@ -33,11 +33,11 @@ class TrackMediaInfoMap {
       const std::vector<rtc::scoped_refptr<RtpReceiverInterface>>&
           rtp_receivers);
 
-  const cricket::VoiceMediaInfo& voice_media_info() const {
-    return *voice_media_info_;
+  const cricket::VoiceMediaInfo* voice_media_info() const {
+    return voice_media_info_.get();
   }
-  const cricket::VideoMediaInfo& video_media_info() const {
-    return *video_media_info_;
+  const cricket::VideoMediaInfo* video_media_info() const {
+    return video_media_info_.get();
   }
 
   const std::vector<cricket::VoiceSenderInfo*>* GetVoiceSenderInfos(