vda_unittest: Verify the visible rectangle of returned picture.

media/gpu/video_decode_accelerator_unittest.cc

Index: media/gpu/video_decode_accelerator_unittest.cc
diff --git a/media/gpu/video_decode_accelerator_unittest.cc b/media/gpu/video_decode_accelerator_unittest.cc
index d76bc615be2e8dfe58d99a60a69fd29fc1006311..e8e32b21b6531cc2bdb993142b3fb2fd8299c93a 100644
--- a/media/gpu/video_decode_accelerator_unittest.cc
+++ b/media/gpu/video_decode_accelerator_unittest.cc
@@ -726,6 +726,9 @@ void GLRenderingVDAClient::PictureReady(const Picture& picture) {
   if (decoder_deleted())
     return;
 
+  gfx::Rect visible_rect = picture.visible_rect();
+  EXPECT_TRUE(visible_rect.IsEmpty() || visible_rect == gfx::Rect(frame_size_));
+
   base::TimeTicks now = base::TimeTicks::Now();
 
   frame_delivery_times_.push_back(now);