Fix WebrtcVideoCapturerAdapter to emit frames even when nothing is changing.

remoting/protocol/webrtc_video_capturer_adapter.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "remoting/protocol/webrtc_video_capturer_adapter.h"
 
 #include <utility>
 
 #include "third_party/libyuv/include/libyuv/convert.h"
 #include "third_party/webrtc/media/engine/webrtcvideoframe.h"
@@ skipping 143 matching lines @@
   return nullptr;
 }
 
 void WebrtcVideoCapturerAdapter::OnCaptureCompleted(
     webrtc::DesktopFrame* frame) {
   DCHECK(thread_checker_.CalledOnValidThread());
 
   DCHECK(capture_pending_);
   capture_pending_ = false;
 
+  if (!frame)
+    return;
+
   scoped_ptr<webrtc::DesktopFrame> owned_frame(frame);
 
-  // Drop the frame if there were no changes.
-  if (!owned_frame || owned_frame->updated_region().is_empty())
-    return;
+  // TODO(sergeyu): Currently the adapter keeps generating frames even when
+  // nothing is changing on the screen. This is necessary because the video
+  // sender drops frames. Obviously this is a suboptimal. The sending code in
+  // WebRTC needs to have some mechanism to notify when the bandwidth is
+  // exceeded, so the capturer can adapt frame rate.
 
   size_t width = frame->size().width();
   size_t height = frame->size().height();
   if (!yuv_frame_ || yuv_frame_->GetWidth() != width ||
       yuv_frame_->GetHeight() != height) {
     if (!size_callback_.is_null())
       size_callback_.Run(frame->size());
 
     scoped_ptr<cricket::WebRtcVideoFrame> webrtc_frame(
         new cricket::WebRtcVideoFrame());
@@ skipping 46 matching lines @@
   DCHECK(thread_checker_.CalledOnValidThread());
 
   if (capture_pending_)
     return;
   capture_pending_ = true;
   desktop_capturer_->Capture(webrtc::DesktopRegion());
 }
 
 }  // namespace protocol
 }  // namespace remoting