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

media/gpu/h264_decoder.cc

Index: media/gpu/h264_decoder.cc
diff --git a/media/gpu/h264_decoder.cc b/media/gpu/h264_decoder.cc
index aed9658374805c9854aaf4c0fa76dc34e67a5412..fe1bf5e73273a5880be48bf0fc47d3d338abd658 100644
--- a/media/gpu/h264_decoder.cc
+++ b/media/gpu/h264_decoder.cc
@@ -1093,6 +1093,12 @@ bool H264Decoder::ProcessSPS(int sps_id, bool* need_new_buffers) {
     return false;
   }
 
+  gfx::Rect new_visible_rect = sps->GetVisibleRect().value_or(gfx::Rect());
+  if (visible_rect_ != new_visible_rect) {
+    DVLOG(2) << "New visible rect: " << new_visible_rect.ToString();
+    visible_rect_ = new_visible_rect;
+  }
+
   int width_mb = new_pic_size.width() / 16;
   int height_mb = new_pic_size.height() / 16;
 
@@ -1351,6 +1357,7 @@ H264Decoder::DecodeResult H264Decoder::Decode() {
           if (!curr_pic_)
             return kRanOutOfSurfaces;
 
+          curr_pic_->visible_rect = visible_rect_;
           if (!StartNewFrame(curr_slice_hdr_.get()))
             SET_ERROR_AND_RETURN();
         }