V4L2SVDA/VAAPIVDA: use visible size from decoder and pass to client

media/gpu/vp8_decoder.h

 // 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.
 
 #ifndef MEDIA_GPU_VP8_DECODER_H_
 #define MEDIA_GPU_VP8_DECODER_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 81 matching lines @@
   std::unique_ptr<Vp8FrameHeader> curr_frame_hdr_;
   scoped_refptr<VP8Picture> curr_pic_;
   scoped_refptr<VP8Picture> last_frame_;
   scoped_refptr<VP8Picture> golden_frame_;
   scoped_refptr<VP8Picture> alt_frame_;
 
   const uint8_t* curr_frame_start_;
   size_t frame_size_;
 
   gfx::Size pic_size_;
+  gfx::Rect visible_rect_;
   int horizontal_scale_;
   int vertical_scale_;
 
   VP8Accelerator* accelerator_;
 
   DISALLOW_COPY_AND_ASSIGN(VP8Decoder);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_GPU_VP8_DECODER_H_