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

media/gpu/accelerated_video_decoder.h

Index: media/gpu/accelerated_video_decoder.h
diff --git a/media/gpu/accelerated_video_decoder.h b/media/gpu/accelerated_video_decoder.h
index ed3db1a50c9e650b16a06ac7c65ff6f6380039a7..8de6d789143442e8072bcaed265e0710e433f5f2 100644
--- a/media/gpu/accelerated_video_decoder.h
+++ b/media/gpu/accelerated_video_decoder.h
@@ -10,6 +10,7 @@
 
 #include "base/macros.h"
 #include "media/gpu/media_gpu_export.h"
+#include "ui/gfx/geometry/rect.h"
 #include "ui/gfx/geometry/size.h"
 
 namespace media {
@@ -57,6 +58,7 @@ class MEDIA_GPU_EXPORT AcceleratedVideoDecoder {
   // be ready to provide for the decoder to function properly.
   // To be used after Decode() returns kAllocateNewSurfaces.
   virtual gfx::Size GetPicSize() const = 0;
+  virtual gfx::Rect GetVisibleRect() const = 0;
   virtual size_t GetRequiredNumOfPictures() const = 0;
 
  private: