chromium/content/test/data/gpu/functional_video.html

<html>
<body>
<video src="../media/bear.ogv" id="video"></video>
<script>
  elem = document.getElementById("video");
  elem.addEventListener("loadedmetadata", function() {
    domAutomationController.send("SUCCESS");
  });
  elem.load();
</script>
</body>
</html>