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

talk/app/webrtc/rtpsender.cc

 /*
  * libjingle
  * Copyright 2015 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 126 matching lines @@
 
 VideoRtpSender::VideoRtpSender(VideoTrackInterface* track,
                                uint32_t ssrc,
                                VideoProviderInterface* provider)
     : id_(track->id()),
       track_(track),
       ssrc_(ssrc),
       provider_(provider),
       cached_track_enabled_(track->enabled()) {
   track_->RegisterObserver(this);
-  VideoSourceInterface* source = track_->GetSource();
-  if (source) {
-    provider_->SetCaptureDevice(ssrc_, source->GetVideoCapturer());
-  }
   Reconfigure();
 }
 
 VideoRtpSender::~VideoRtpSender() {
   track_->UnregisterObserver(this);
   Stop();
 }
 
 void VideoRtpSender::OnChanged() {
   if (cached_track_enabled_ != track_->enabled()) {
     cached_track_enabled_ = track_->enabled();
-    Reconfigure();
+    SetVideoSend();
   }
 }
 
 bool VideoRtpSender::SetTrack(MediaStreamTrackInterface* track) {
   if (track->kind() != "video") {
     LOG(LS_ERROR) << "SetTrack called on video RtpSender with " << track->kind()
                   << " track.";
     return false;
   }
   VideoTrackInterface* video_track = static_cast<VideoTrackInterface*>(track);
@@ skipping 16 matching lines @@
   }
   provider_->SetCaptureDevice(ssrc_, nullptr);
   provider_->SetVideoSend(ssrc_, false, nullptr);
   provider_ = nullptr;
 }
 
 void VideoRtpSender::Reconfigure() {
   if (!provider_) {
     return;
   }
+  VideoSourceInterface* source = track_->GetSource();
+  if (source) {
+    provider_->SetCaptureDevice(ssrc_, source->GetVideoCapturer());

[pthatcher1, 2015/11/11 00:45:02]

Is there any downside to calling this all the time?  In other words, to just
call Reconfigure() all the time and not have a separate SetVideoSend?

[Taylor Brandstetter, 2015/11/11 01:33:30]

If you trace your way down to
WebRtcVideoChannel2::WebRtcVideoSendStream::SetCapturer, it definitely seems to
have some undesired effects. I plan to merge SetVideoSend and SetCapturer in a
later CL though, and then we can get rid of "ReconfigureEverythingButCapturer"

+  }
+  SetVideoSend();
+}
+
+void VideoRtpSender::SetVideoSend() {

[pthatcher1, 2015/11/11 00:45:02]

Actually, if this is separate, calling something like "ReconfigureJustX" or
"ReconfigureEverythingExceptX" might make sense.  Perhaps
"ReconfigureEverythingExceptCaptureDevice".  It's verbose, but it's at least
clear what the intention is.

[Taylor Brandstetter, 2015/11/11 01:33:30]

Done.

+  if (!provider_) {
+    return;
+  }
+  VideoSourceInterface* source = track_->GetSource();
   const cricket::VideoOptions* options = nullptr;
-  VideoSourceInterface* source = track_->GetSource();
   if (track_->enabled() && source) {
     options = source->options();
   }
   provider_->SetVideoSend(ssrc_, track_->enabled(), options);
 }
 
 }  // namespace webrtc