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

talk/app/webrtc/peerconnection.cc

Index: talk/app/webrtc/peerconnection.cc
diff --git a/talk/app/webrtc/peerconnection.cc b/talk/app/webrtc/peerconnection.cc
index caa892d00b9b04802c15908b04f97bd4ddf3cfb1..efdea66a0f5bc639abfe0f870da5e40b2668f7eb 100644
--- a/talk/app/webrtc/peerconnection.cc
+++ b/talk/app/webrtc/peerconnection.cc
@@ -1088,6 +1088,8 @@ void PeerConnection::SetRemoteDescription(
 
   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());
@@ -1098,6 +1100,7 @@ void PeerConnection::SetRemoteDescription(
   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*>(
@@ -1116,6 +1119,7 @@ void PeerConnection::SetRemoteDescription(
   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*>(
@@ -1147,14 +1151,8 @@ void PeerConnection::SetRemoteDescription(
     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);
@@ -1503,14 +1501,14 @@ void PeerConnection::UpdateRemoteStreamsList(
   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 {
@@ -1533,6 +1531,9 @@ void PeerConnection::UpdateRemoteStreamsList(
       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 =
@@ -1604,6 +1605,40 @@ void PeerConnection::UpdateEndedRemoteMediaStreams() {
   }
 }
 
+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;