<!DOCTYPE html>

<html>
<head>
  <style type="text/css" media="screen">
    iframe {
        border: 10px solid black;
        padding: 5px;
        margin: 20px;
        height: 150px;
        width: 0;
    }
    
    .expanded {
      width: 300px;
    }
    
    .overlay {
      position: absolute;
      width: 50px;
      height: 50px;
      top: 5px;
      left: 5px;
      background-color: rgba(0, 0, 0, 0.2);
    }
    
  </style>
  <script type="text/javascript" charset="utf-8">
    if (window.testRunner) {
        testRunner.dumpAsText();
        testRunner.waitUntilDone();
    }

    function doTest()
    {
        window.setTimeout(function() {
            document.getElementById('iframe').className = 'expanded';
            // Need to wait for compositing layers to be updated.
            window.setTimeout(function() {
                if (window.testRunner) {
                    document.getElementById('layers').innerHTML = window.internals.layerTreeAsText(document);
                    testRunner.notifyDone();
                }
            }, 0);
        }, 0);
    }

    window.addEventListener('load', doTest, false);
  </script>
</head>
<body>

    <!-- The parent document may into compositing mode by the iframe. -->
    <iframe id="iframe" src="resources/composited-subframe.html"></iframe>
    
    <div class="overlay">
    </div>

    <pre id="layers">Layer tree appears here in DRT.</pre>
</body>
</html>