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

media/gpu/vp9_decoder.h

Index: media/gpu/vp9_decoder.h
diff --git a/media/gpu/vp9_decoder.h b/media/gpu/vp9_decoder.h
index d2264b595f42b6544bc85377cdc2d1b777e8ba75..cbff9c618f11dfb4003b22e30755997e18d53b7c 100644
--- a/media/gpu/vp9_decoder.h
+++ b/media/gpu/vp9_decoder.h
@@ -101,6 +101,7 @@ class MEDIA_GPU_EXPORT VP9Decoder : public AcceleratedVideoDecoder {
   void Reset() override;
   DecodeResult Decode() override WARN_UNUSED_RESULT;
   gfx::Size GetPicSize() const override;
+  gfx::Rect GetVisibleRect() const override;
   size_t GetRequiredNumOfPictures() const override;
 
  private:
@@ -139,6 +140,8 @@ class MEDIA_GPU_EXPORT VP9Decoder : public AcceleratedVideoDecoder {
 
   // Current coded resolution.
   gfx::Size pic_size_;
+  // Current render resolution.
+  gfx::Rect render_rect_;
 
   // VP9Accelerator instance owned by the client.
   VP9Accelerator* accelerator_;