Supply empty frames until codec is done with top-off.

remoting/codec/video_encoder_vpx.h

 // Copyright 2013 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_CODEC_VIDEO_ENCODER_VPX_H_
 #define REMOTING_CODEC_VIDEO_ENCODER_VPX_H_
 
 #include "base/callback.h"
 #include "base/time/time.h"
 #include "remoting/codec/scoped_vpx_codec.h"
@@ skipping 55 matching lines @@
 
   // Used to generate zero-based frame timestamps.
   base::TimeTicks timestamp_base_;
 
   // VPX image and buffer to hold the actual YUV planes.
   scoped_ptr<vpx_image_t> image_;
   scoped_ptr<uint8[]> image_buffer_;
 
   // Active map used to optimize out processing of un-changed macroblocks.
   scoped_ptr<uint8[]> active_map_;
-  int active_map_width_ = 0;
-  int active_map_height_ = 0;
+  webrtc::DesktopSize active_map_size_;
 
-  // Number of "top-off" frames we've encoded since we were last passed a
-  // frame containing an actual change. Used only when encoding with top-off.
-  int topoff_frame_count_ = 0;
+  // True if the codec wants unchanged frames to finish topping-off with.
+  bool encode_unchanged_frame_;
 
   // Used to help initialize VideoPackets from DesktopFrames.
   VideoEncoderHelper helper_;
 
   DISALLOW_COPY_AND_ASSIGN(VideoEncoderVpx);
 };
 
 }  // namespace remoting
 
 #endif  // REMOTING_CODEC_VIDEO_ENCODER_VP8_H_