LayoutTests/media/video-controls-in-media-document.html

<p>Test that controls don't increase the size of the container (i.e. are
rendered overlapping with the video canvas).<p>
<script src="media-file.js" type="text/javascript"></script>
<script src="video-test.js" type="text/javascript"></script>

<iframe style="width: 400px; height: 300px; border: 0px;" id="container"> </iframe>

<script type="text/javascript">
var iframe = document.getElementById("container");

function timeupdate(event) {
    var video = event.target;
    controls = internals.shadowRoot(video).firstChild.firstChild;
    testExpected("controls.offsetTop + controls.offsetHeight", video.offsetHeight, "<=");
    testRunner.notifyDone();
};

function start() {
    var iframeDocument = document.getElementById("container").contentDocument;
    var video = iframeDocument.querySelector("video");
    video.addEventListener("timeupdate", timeupdate);
};

iframe.onload = start;
iframe.src = findMediaFile("video", "content/test");
</script>