chromium/third_party/blink/web_tests/fast/overflow/overflow-of-video-outline.html

<!doctype HTML>
<head>
</head>
<script src="../../media/media-controls.js"></script>

 <video id=video  controls width=400>
  </video>
<script>
if (window.testRunner)
    testRunner.waitUntilDone();
onload = runTest;

var play_button = mediaControlsButton(video, "play-button");
var timeline = mediaControlsButton(video, "timeline");

function runTest() {
    requestAnimationFrame(focusPlayButton);
}

function focusPlayButton() {
    play_button.style.outline = "2px solid black";
    requestAnimationFrame(focusTimeline);
}

function focusTimeline() {
    play_button.style.outline = "";
    timeline.style.outline = "2px solid black";
    testRunner.notifyDone();
}
</script>