Get VideoCapturer stats via VideoTrackSourceInterface in StatsCollector,

webrtc/api/videocapturertracksource.cc

 /*
  *  Copyright 2012 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 342 matching lines @@
   if (!worker_thread()->Invoke<bool>(
           rtc::Bind(&cricket::VideoCapturer::StartCapturing,
                     video_capturer_.get(), format_))) {
     SetState(kEnded);
     return;
   }
   started_ = true;
   // Initialize hasn't succeeded until a successful state change has occurred.
 }
 
+bool VideoCapturerTrackSource::GetStats(Stats* stats) {
+  return video_capturer_->GetInputSize(&stats->input_width,
+                                       &stats->input_height);
+}
+
 void VideoCapturerTrackSource::Stop() {
   if (!started_) {
     return;
   }
   started_ = false;
   worker_thread()->Invoke<void>(
       rtc::Bind(&cricket::VideoCapturer::Stop, video_capturer_.get()));
 }
 
 void VideoCapturerTrackSource::Restart() {
@@ skipping 19 matching lines @@
                                      this, capturer, capture_state));
     return;
   }
 
   if (capturer == video_capturer_.get()) {
     SetState(GetReadyState(capture_state));
   }
 }
 
 }  // namespace webrtc