See:
https://cs.chromium.org/chromium/src/third_party/WebKit/LayoutTests/media/webkit-media-controls-webkit-appearance.html

It will be available under: virtual/video-surface-layer/media/webkit-media-controls-webkit-appearance.html soon. When opening the file and the expectation, they look very similar. But the screenshot seems to interlace the <div> and the <video> such as the <div> can be seen below the video.