[Chromoting] Implement DualBufferFrameConsumer

remoting/client/gl_desktop.h

 // Copyright 2016 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.
 
 #ifndef REMOTING_CLIENT_OPENGL_GL_DESKTOP_H_
 #define REMOTING_CLIENT_OPENGL_GL_DESKTOP_H_
 
 #include <memory>
 
 #include "base/macros.h"
+#include "third_party/webrtc/modules/desktop_capture/desktop_geometry.h"
 
 namespace webrtc {
 class DesktopFrame;
-class DesktopRegion;
 }  // namespace webrtc
 
 namespace remoting {
 
 class GlCanvas;
 class GlRenderLayer;
 
 // This class draws the desktop on the canvas.
 class GlDesktop {
  public:
   GlDesktop();
   virtual ~GlDesktop();
 
+  // frame can be either a full frame or updated regions only frame.

[Sergey Ulanov, 2016/07/22 18:04:19]

s/frame can/|frame| can/

[Yuwei, 2016/07/22 18:35:15]

Done.

   void SetVideoFrame(std::unique_ptr<webrtc::DesktopFrame> frame);
 
-  // Sets the canvas on which the desktop will be drawn. Resumes the current
-  // state of the desktop to the context of the new canvas.
+  // Sets the canvas on which the desktop will be drawn. Caller must feed a
+  // full desktop frame after calling this function.
   // If |canvas| is nullptr, nothing will happen when calling Draw().
   void SetCanvas(GlCanvas* canvas);
 
   // Draws the desktop on the canvas.
   void Draw();
 
  private:
   std::unique_ptr<GlRenderLayer> layer_;
-  std::unique_ptr<webrtc::DesktopFrame> last_frame_;
+  webrtc::DesktopSize last_desktop_size_;
 
   DISALLOW_COPY_AND_ASSIGN(GlDesktop);
 };
 
 }  // namespace remoting
 
 #endif  // REMOTING_CLIENT_OPENGL_GL_DESKTOP_H_