chrome/test/data/media/engagement/engagement_autoplay_iframe_test.html - chromium/src - Git at Google

 <!DOCTYPE html>
 <meta charset="utf-8">
 <title>Media Engagement Test</title>
 <iframe name="subframe" frameborder="0" style="width:500px;height:500px"></iframe>
 <script>
 window.addEventListener("message", function(e) {
   window.document.title = e.data;
 }, false);
 </script>
	<!DOCTYPE html>
	<meta charset="utf-8">
	<title>Media Engagement Test</title>
	<iframe name="subframe" frameborder="0" style="width:500px;height:500px"></iframe>
	<script>
	window.addEventListener("message", function(e) {
	window.document.title = e.data;
	}, false);
	</script>