Fix for scenario where m-line is revived after being set to port 0.

talk/app/webrtc/peerconnection.h

Index: talk/app/webrtc/peerconnection.h
diff --git a/talk/app/webrtc/peerconnection.h b/talk/app/webrtc/peerconnection.h
index 2d388ae9f913912990af0541dd8eae67008da745..b2cf3a93b0685021f1be6cdaf9f78eeb78792ca8 100644
--- a/talk/app/webrtc/peerconnection.h
+++ b/talk/app/webrtc/peerconnection.h
@@ -333,6 +333,9 @@ class PeerConnection : public PeerConnectionInterface,
   std::vector<rtc::scoped_refptr<RtpReceiverInterface>>::iterator
   FindReceiverForTrack(MediaStreamTrackInterface* track);
 
+  void ReconfigureSenders(cricket::MediaType media_type);
+  void ReconfigureReceivers(cricket::MediaType media_type);
+
   TrackInfos* GetRemoteTracks(cricket::MediaType media_type);
   TrackInfos* GetLocalTracks(cricket::MediaType media_type);
   const TrackInfo* FindTrackInfo(const TrackInfos& infos,
@@ -372,6 +375,11 @@ class PeerConnection : public PeerConnectionInterface,
   TrackInfos local_audio_tracks_;
   TrackInfos local_video_tracks_;
 
+  // Flags indicating whether or not audio/video was rejected
+  // in the last description set.
+  bool audio_rejected_ = false;
+  bool video_rejected_ = false;
+
   SctpSidAllocator sid_allocator_;
   // label -> DataChannel
   std::map<std::string, rtc::scoped_refptr<DataChannel>> rtp_data_channels_;