Crop ImageBitmaps from VideoFrames

This CL adds consideration for a frame's visible_rect when creating an
image bitmap, instead of using only the coded_rect. This fixes rows of
pixels being repeated at the bottom of an image.

Bug: 1145244
Change-Id: I534a9e768203ceee889827c370d2acfd574c77fe
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2518108Reviewed-by: Dan Sanders <sandersd@chromium.org>
Commit-Queue: Thomas Guilbert <tguilbert@chromium.org>
Cr-Commit-Position: refs/heads/master@{#823786}

third_party/blink/renderer/modules/webcodecs/video_frame.cc

@@ -315,8 +315,13 @@ scoped_refptr<const media::VideoFrame> VideoFrame::frame() const {
 ScriptPromise VideoFrame::createImageBitmap(ScriptState* script_state,
                                             const ImageBitmapOptions* options,
                                             ExceptionState& exception_state) {
-  return ImageBitmapFactories::CreateImageBitmap(
-      script_state, this, base::Optional<IntRect>(), options, exception_state);
+  base::Optional<IntRect> crop_rect;
+
+  if (auto local_frame = handle_->frame())
+    crop_rect = IntRect(local_frame->visible_rect());
+
+  return ImageBitmapFactories::CreateImageBitmap(script_state, this, crop_rect,
+                                                 options, exception_state);
 }
 
 IntSize VideoFrame::BitmapSourceSize() const {