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

talk/app/webrtc/peerconnection.cc

 /*
  * 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 1070 matching lines @@
   // If setting the description decided our SSL role, allocate any necessary
   // SCTP sids.
   rtc::SSLRole role;
   if (session_->data_channel_type() == cricket::DCT_SCTP &&
       session_->GetSslRole(&role)) {
     AllocateSctpSids(role);
   }
 
   const cricket::SessionDescription* remote_desc = desc->description();
 
+  remote_info_.msid_supported |= remote_desc->msid_supported();
+
   // We wait to signal new streams until we finish processing the description,
   // since only at that point will new streams have all their tracks.
   rtc::scoped_refptr<StreamCollection> new_streams(StreamCollection::Create());
 
   // Find all audio rtp streams and create corresponding remote AudioTracks
   // and MediaStreams.
   const cricket::ContentInfo* audio_content = GetFirstAudioContent(remote_desc);
   if (audio_content) {
     if (audio_content->rejected) {
       RemoveTracks(cricket::MEDIA_TYPE_AUDIO);
+      remote_info_.default_audio_track_needed = false;
     } else {
       const cricket::AudioContentDescription* desc =
           static_cast<const cricket::AudioContentDescription*>(
               audio_content->description);
       UpdateRemoteStreamsList(GetActiveStreams(desc), desc->type(),
                               new_streams);
       remote_info_.default_audio_track_needed =
           !remote_desc->msid_supported() && desc->streams().empty() &&
           MediaContentDirectionHasSend(desc->direction());
     }
   }
 
   // Find all video rtp streams and create corresponding remote VideoTracks
   // and MediaStreams.
   const cricket::ContentInfo* video_content = GetFirstVideoContent(remote_desc);
   if (video_content) {
     if (video_content->rejected) {
       RemoveTracks(cricket::MEDIA_TYPE_VIDEO);
+      remote_info_.default_video_track_needed = false;
     } else {
       const cricket::VideoContentDescription* desc =
           static_cast<const cricket::VideoContentDescription*>(
               video_content->description);
       UpdateRemoteStreamsList(GetActiveStreams(desc), desc->type(),
                               new_streams);
       remote_info_.default_video_track_needed =
           !remote_desc->msid_supported() && desc->streams().empty() &&
           MediaContentDirectionHasSend(desc->direction());
     }
@@ skipping 11 matching lines @@
     }
   }
 
   // Iterate new_streams and notify the observer about new MediaStreams.
   for (size_t i = 0; i < new_streams->count(); ++i) {
     MediaStreamInterface* new_stream = new_streams->at(i);
     stats_->AddStream(new_stream);
     observer_->OnAddStream(new_stream);
   }
 
-  // Find removed MediaStreams.
-  if (remote_info_.IsDefaultMediaStreamNeeded() &&
-      remote_streams_->find(kDefaultStreamLabel) != nullptr) {
-    // The default media stream already exists. No need to do anything.
-  } else {
-    UpdateEndedRemoteMediaStreams();
-    remote_info_.msid_supported |= remote_streams_->count() > 0;
-  }
+  MaybeRemoveDefaultTracks();
+  UpdateEndedRemoteMediaStreams();
   MaybeCreateDefaultStream();
 
   SetSessionDescriptionMsg* msg = new SetSessionDescriptionMsg(observer);
   signaling_thread()->Post(this, MSG_SET_SESSIONDESCRIPTION_SUCCESS, msg);
 }
 
 bool PeerConnection::SetConfiguration(const RTCConfiguration& config) {
   if (port_allocator_) {
     std::vector<PortAllocatorFactoryInterface::StunConfiguration> stuns;
     std::vector<PortAllocatorFactoryInterface::TurnConfiguration> turns;
@@ skipping 328 matching lines @@
                           nullptr);
 }
 
 void PeerConnection::UpdateRemoteStreamsList(
     const cricket::StreamParamsVec& streams,
     cricket::MediaType media_type,
     StreamCollection* new_streams) {
   TrackInfos* current_tracks = GetRemoteTracks(media_type);
 
   // Find removed tracks. I.e., tracks where the track id or ssrc don't match
-  // the
-  // new StreamParam.
+  // the new StreamParam.
   auto track_it = current_tracks->begin();
   while (track_it != current_tracks->end()) {
     const TrackInfo& info = *track_it;
     const cricket::StreamParams* params =
         cricket::GetStreamBySsrc(streams, info.ssrc);
-    if (!params || params->id != info.track_id) {
+    if (info.stream_label != kDefaultStreamLabel &&

[pthatcher1, 2015/12/02 22:05:53]

Would it be cleaner to put this inside of UpdateRemoteStreamList?

if (info.stream_label == kDefaultStreamLabel) {
  if (!remote_info_.IsDefaultMediaStreamNeeded() ||
      !remote_info_.default_audio_track_needed)) {	
    OnRemoteTrackRemoved(info.stream_label, info.track_id, media_type);
    track_it = current_tracks->erase(track_it);
   }
} else ... {
}

And then call UpdateRemoteStreamList inside of SetRemoteDescription in both the
rejected and non-rejected cases?

+        (!params || params->id != info.track_id)) {
       OnRemoteTrackRemoved(info.stream_label, info.track_id, media_type);
       track_it = current_tracks->erase(track_it);
     } else {
       ++track_it;
     }
   }
 
   // Find new and active tracks.
   for (const cricket::StreamParams& params : streams) {
     // The sync_label is the MediaStream label and the |stream.id| is the
     // track id.
     const std::string& stream_label = params.sync_label;
     const std::string& track_id = params.id;
     uint32_t ssrc = params.first_ssrc();
 
     rtc::scoped_refptr<MediaStreamInterface> stream =
         remote_streams_->find(stream_label);
     if (!stream) {
       // This is a new MediaStream. Create a new remote MediaStream.
       stream = remote_stream_factory_->CreateMediaStream(stream_label);
       remote_streams_->AddStream(stream);
       new_streams->AddStream(stream);
+      // Just in case the peer supports MSID, but doesn't indicate so with
+      // "a=msid-semantic"...
+      remote_info_.msid_supported = true;
     }
 
     const TrackInfo* track_info =
         FindTrackInfo(*current_tracks, stream_label, track_id);
     if (!track_info) {
       current_tracks->push_back(TrackInfo(stream_label, track_id, ssrc));
       OnRemoteTrackSeen(stream_label, track_id, ssrc, media_type);
     }
   }
 }
@@ skipping 51 matching lines @@
       streams_to_remove.push_back(stream);
     }
   }
 
   for (const auto& stream : streams_to_remove) {
     remote_streams_->RemoveStream(stream);
     observer_->OnRemoveStream(stream);
   }
 }
 
+void PeerConnection::MaybeRemoveDefaultTracks() {
+  rtc::scoped_refptr<MediaStreamInterface> default_remote_stream =
+      remote_streams_->find(kDefaultStreamLabel);
+  if (!default_remote_stream) {
+    return;
+  }
+
+  if ((!remote_info_.IsDefaultMediaStreamNeeded() ||
+       !remote_info_.default_audio_track_needed) &&
+      default_remote_stream->GetAudioTracks().size() > 0) {
+    auto it =
+        std::find(remote_audio_tracks_.begin(), remote_audio_tracks_.end(),
+                  TrackInfo(kDefaultStreamLabel, kDefaultAudioTrackLabel, 0));
+    if (it != remote_audio_tracks_.end()) {
+      OnRemoteTrackRemoved(kDefaultStreamLabel, kDefaultAudioTrackLabel,
+                           cricket::MEDIA_TYPE_AUDIO);
+      remote_audio_tracks_.erase(it);
+    }
+  }
+
+  if ((!remote_info_.IsDefaultMediaStreamNeeded() ||
+       !remote_info_.default_video_track_needed) &&
+      default_remote_stream->GetVideoTracks().size() > 0) {
+    auto it =
+        std::find(remote_video_tracks_.begin(), remote_video_tracks_.end(),
+                  TrackInfo(kDefaultStreamLabel, kDefaultVideoTrackLabel, 0));
+    if (it != remote_video_tracks_.end()) {
+      OnRemoteTrackRemoved(kDefaultStreamLabel, kDefaultVideoTrackLabel,
+                           cricket::MEDIA_TYPE_VIDEO);
+      remote_video_tracks_.erase(it);
+    }
+  }
+}
+
 void PeerConnection::MaybeCreateDefaultStream() {
   if (!remote_info_.IsDefaultMediaStreamNeeded()) {
     return;
   }
 
   bool default_created = false;
 
   rtc::scoped_refptr<MediaStreamInterface> default_remote_stream =
       remote_streams_->find(kDefaultStreamLabel);
   if (default_remote_stream == nullptr) {
@@ skipping 412 matching lines @@
 DataChannel* PeerConnection::FindDataChannelBySid(int sid) const {
   for (const auto& channel : sctp_data_channels_) {
     if (channel->id() == sid) {
       return channel;
     }
   }
   return nullptr;
 }
 
 }  // namespace webrtc