Extended proxy abstraction, to call certain methods to the worker thread.

webrtc/api/videotrack.cc

 /*
  *  Copyright 2011 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.
  */
 
 #include "webrtc/api/videotrack.h"
 
 #include <string>
 
 namespace webrtc {
 
 const char MediaStreamTrackInterface::kVideoKind[] = "video";
 
 VideoTrack::VideoTrack(const std::string& label,
                        VideoTrackSourceInterface* video_source)
     : MediaStreamTrack<VideoTrackInterface>(label),
       video_source_(video_source) {
+  worker_thread_checker_.DetachFromThread();
   video_source_->RegisterObserver(this);
 }
 
 VideoTrack::~VideoTrack() {
   video_source_->UnregisterObserver(this);
 }
 
 std::string VideoTrack::kind() const {
   return kVideoKind;
 }
 
+// AddOrUpdateSink and RemoveSink should be called on the worker
+// thread.
 void VideoTrack::AddOrUpdateSink(
     rtc::VideoSinkInterface<cricket::VideoFrame>* sink,
     const rtc::VideoSinkWants& wants) {
-  RTC_DCHECK(thread_checker_.CalledOnValidThread());
+  RTC_DCHECK(worker_thread_checker_.CalledOnValidThread());
   VideoSourceBase::AddOrUpdateSink(sink, wants);
   rtc::VideoSinkWants modified_wants = wants;
   modified_wants.black_frames = !enabled();
   video_source_->AddOrUpdateSink(sink, modified_wants);
 }
 
 void VideoTrack::RemoveSink(
     rtc::VideoSinkInterface<cricket::VideoFrame>* sink) {
-  RTC_DCHECK(thread_checker_.CalledOnValidThread());
+  RTC_DCHECK(worker_thread_checker_.CalledOnValidThread());
   VideoSourceBase::RemoveSink(sink);
   video_source_->RemoveSink(sink);
 }
 
 bool VideoTrack::set_enabled(bool enable) {
-  RTC_DCHECK(thread_checker_.CalledOnValidThread());
+  RTC_DCHECK(signaling_thread_checker_.CalledOnValidThread());
   for (auto& sink_pair : sink_pairs()) {
     rtc::VideoSinkWants modified_wants = sink_pair.wants;
     modified_wants.black_frames = !enable;
+    // video_source_ is a proxy object, marshalling the call to the
+    // worker thread.
     video_source_->AddOrUpdateSink(sink_pair.sink, modified_wants);
   }
   return MediaStreamTrack<VideoTrackInterface>::set_enabled(enable);
 }
 
 void VideoTrack::OnChanged() {
-  RTC_DCHECK(thread_checker_.CalledOnValidThread());
+  RTC_DCHECK(signaling_thread_checker_.CalledOnValidThread());
   if (video_source_->state() == MediaSourceInterface::kEnded) {
     set_state(kEnded);
   } else {
     set_state(kLive);
   }
 }
 
 rtc::scoped_refptr<VideoTrack> VideoTrack::Create(
     const std::string& id,
     VideoTrackSourceInterface* source) {
   rtc::RefCountedObject<VideoTrack>* track =
       new rtc::RefCountedObject<VideoTrack>(id, source);
   return track;
 }
 
 }  // namespace webrtc