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

media/gpu/h264_decoder.h

Index: media/gpu/h264_decoder.h
diff --git a/media/gpu/h264_decoder.h b/media/gpu/h264_decoder.h
index 1caf662a7a6fa07b68b069321e014195fd6f28fd..95023169052bfaa33a3ce9f2433771bfd501d54b 100644
--- a/media/gpu/h264_decoder.h
+++ b/media/gpu/h264_decoder.h
@@ -109,6 +109,7 @@ class MEDIA_GPU_EXPORT H264Decoder : public AcceleratedVideoDecoder {
   void SetStream(const uint8_t* ptr, size_t size) override;
   DecodeResult Decode() override WARN_UNUSED_RESULT;
   gfx::Size GetPicSize() const override;
+  gfx::Rect GetVisibleRect() const override;
   size_t GetRequiredNumOfPictures() const override;
 
  private:
@@ -266,6 +267,8 @@ class MEDIA_GPU_EXPORT H264Decoder : public AcceleratedVideoDecoder {
 
   // Output picture size.
   gfx::Size pic_size_;
+  // Output visible cropping rect.
+  gfx::Rect visible_rect_;
 
   // PicOrderCount of the previously outputted frame.
   int last_output_poc_;