Adding more detail to MessageQueue::Dispatch logging.

webrtc/sdk/objc/Framework/Classes/avfoundationvideocapturer.mm

 /*
  *  Copyright 2015 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 606 matching lines @@
 
   CVImageBufferRef image_buffer = CMSampleBufferGetImageBuffer(sampleBuffer);
   if (image_buffer == NULL) {
     return;
   }
 
   // Retain the buffer and post it to the webrtc thread. It will be released
   // after it has successfully been signaled.
   CVBufferRetain(image_buffer);
   AVFoundationFrame frame(image_buffer, rtc::TimeNanos());
-  _startThread->Post(this, kMessageTypeFrame,
+  _startThread->Post(RTC_FROM_HERE, this, kMessageTypeFrame,
                      new rtc::TypedMessageData<AVFoundationFrame>(frame));
 }
 
 void AVFoundationVideoCapturer::OnMessage(rtc::Message *msg) {
   switch (msg->message_id) {
     case kMessageTypeFrame: {
       rtc::TypedMessageData<AVFoundationFrame>* data =
         static_cast<rtc::TypedMessageData<AVFoundationFrame>*>(msg->pdata);
       const AVFoundationFrame& frame = data->data();
       OnFrameMessage(frame.image_buffer, frame.capture_time);
@@ skipping 52 matching lines @@
 
   // This will call a superclass method that will perform the frame conversion
   // to I420.
   SignalFrameCaptured(this, &frame);
 
   CVPixelBufferUnlockBaseAddress(image_buffer, lock_flags);
   CVBufferRelease(image_buffer);
 }
 
 }  // namespace webrtc