Fixing issue with default stream upon setting 2nd remote description.

talk/app/webrtc/peerconnection.h

 /*
  * libjingle
  * Copyright 2012 Google Inc.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
  *
  *  1. Redistributions of source code must retain the above copyright notice,
  *     this list of conditions and the following disclaimer.
  *  2. Redistributions in binary form must reproduce the above copyright notice,
@@ skipping 140 matching lines @@
  protected:
   ~PeerConnection() override;
 
  private:
   struct TrackInfo {
     TrackInfo() : ssrc(0) {}
     TrackInfo(const std::string& stream_label,
               const std::string track_id,
               uint32_t ssrc)
         : stream_label(stream_label), track_id(track_id), ssrc(ssrc) {}
+    bool operator==(const TrackInfo& other) {
+      return this->stream_label == other.stream_label &&
+             this->track_id == other.track_id && this->ssrc == other.ssrc;
+    }
     std::string stream_label;
     std::string track_id;
     uint32_t ssrc;
   };
   typedef std::vector<TrackInfo> TrackInfos;
 
   struct RemotePeerInfo {
     RemotePeerInfo()
         : msid_supported(false),
           default_audio_track_needed(false),
@@ skipping 101 matching lines @@
   // MediaStream and triggers DestroyAudioReceiver or DestroyVideoReceiver.
   void OnRemoteTrackRemoved(const std::string& stream_label,
                             const std::string& track_id,
                             cricket::MediaType media_type);
 
   // Finds remote MediaStreams without any tracks and removes them from
   // |remote_streams_| and notifies the observer that the MediaStreams no longer
   // exist.
   void UpdateEndedRemoteMediaStreams();
 
+  void MaybeRemoveDefaultTracks();
   void MaybeCreateDefaultStream();
 
   // Set the MediaStreamTrackInterface::TrackState to |kEnded| on all remote
   // tracks of type |media_type|.
   void EndRemoteTracks(cricket::MediaType media_type);
 
   // Loops through the vector of |streams| and finds added and removed
   // StreamParams since last time this method was called.
   // For each new or removed StreamParam, OnLocalTrackSeen or
   // OnLocalTrackRemoved is invoked.
@@ skipping 109 matching lines @@
   // because its destruction fires signals (such as VoiceChannelDestroyed)
   // which will trigger some final actions in PeerConnection...
   rtc::scoped_ptr<WebRtcSession> session_;
   // ... But stats_ depends on session_ so it should be destroyed even earlier.
   rtc::scoped_ptr<StatsCollector> stats_;
 };
 
 }  // namespace webrtc
 
 #endif  // TALK_APP_WEBRTC_PEERCONNECTION_H_