Make cricket::VideoFrame inherit webrtc::VideoFrame.

webrtc/media/devices/gtkvideorenderer.h

 /*
  *  Copyright (c) 2004 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.
  */
 
 // Definition of class GtkVideoRenderer that implements the abstract class
 // cricket::VideoRenderer via GTK.
 
 #ifndef WEBRTC_MEDIA_DEVICES_GTKVIDEORENDERER_H_
 #define WEBRTC_MEDIA_DEVICES_GTKVIDEORENDERER_H_
 
 #include <memory>
 
 #include "webrtc/base/basictypes.h"
+#include "webrtc/media/base/videoframe.h"
 #include "webrtc/media/base/videosinkinterface.h"
 
 typedef struct _GtkWidget GtkWidget;  // forward declaration, defined in gtk.h
 
 namespace cricket {
 
+// TODO(nisse): For some reason, forward declaration doens't work when
+// the definition is a "using" alias.
+#if 0
 class VideoFrame;
+#endif
 
 class GtkVideoRenderer : public rtc::VideoSinkInterface<VideoFrame> {
  public:
   GtkVideoRenderer(int x, int y);
   virtual ~GtkVideoRenderer();
 
   // Implementation of VideoSinkInterface.
   void OnFrame(const VideoFrame& frame) override;
 
  private:
@@ skipping 12 matching lines @@
   int initial_x_;
   int initial_y_;
 
   int width_;
   int height_;
 };
 
 }  // namespace cricket
 
 #endif  // WEBRTC_MEDIA_DEVICES_GTKVIDEORENDERER_H_