Add VideoLayout message.

remoting/protocol/video_frame_pump.cc

Index: remoting/protocol/video_frame_pump.cc
diff --git a/remoting/protocol/video_frame_pump.cc b/remoting/protocol/video_frame_pump.cc
index 0a6d963a0cf4ed24385bcda214811c2a3e10983e..072b2fd059eb7076802bd28a65e8833c6f1f92c8 100644
--- a/remoting/protocol/video_frame_pump.cc
+++ b/remoting/protocol/video_frame_pump.cc
@@ -122,10 +122,12 @@ void VideoFramePump::OnCaptureCompleted(webrtc::DesktopFrame* frame) {
 
   captured_frame_timestamps_->capture_ended_time = base::TimeTicks::Now();
 
-  if (frame && !frame_size_.equals(frame->size())) {
+  if (frame && (!frame_size_.equals(frame->size()) ||
+                !frame_dpi_.equals(frame->dpi()))) {
     frame_size_ = frame->size();
+    frame_dpi_ = frame->dpi();
     if (!size_callback_.is_null())
-      size_callback_.Run(frame_size_);
+      size_callback_.Run(frame_size_, frame_dpi_);
   }
 
   // Even when |frame| is nullptr we still need to post it to the encode thread