Replace SetCapturer and SetCaptureDevice by SetSource.

webrtc/api/videotracksource.cc

 /*
  *  Copyright 2016 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 39 matching lines @@
 void VideoTrackSource::RemoveSink(
     rtc::VideoSinkInterface<cricket::VideoFrame>* sink) {
   if (!source_) {
     return;
   }
   worker_thread_->Invoke<void>(
       rtc::Bind(&rtc::VideoSourceInterface<cricket::VideoFrame>::RemoveSink,
                 source_, sink));
 }
 
+void VideoTrackSource::GetInfo(rtc::VideoSourceInfo *info) {
+  if (source_)
+    source_->GetInfo(info);

[perkj_webrtc, 2016/03/20 15:01:46]

Humm. This looks like a potential race with OnSourceDestroyed. 
Actually - you call GetInfo on the worker thread from webrtcvideoengine2.
Everything else in this class is called on the signaling thread. 

[nisse-webrtc, 2016/03/23 14:07:02]

I'd need some guidance on how to get the threading right. As for
OnSourceDestroyed, it seems like calling GetInfo at the same time (or after) the
source is destroyed is a plain use-after-free. It should be invalid to destroy a
source while it is registered with VideoMediaChannel->SetSource, right?

[perkj_webrtc, 2016/03/24 11:02:50]

That is correct. And should in practice never happen since it means we have a
bug else where. Maybe we can just document that somehow. 

+}
+
+
 }  //  namespace webrtc