<!DOCTYPE html>

<html>
<head>
    <style>
        .spacer {
            height: 350px;
            width: 100%;
            margin: 10px;
            background-color: silver;
        }
        .box {
            height: 100px;
            width: 100px;
            margin: 10px;
            border: 1px solid black;
            background-color: blue;
        }
        .composited {
            -webkit-transform: translateZ(0);
            box-shadow: 0 0 10px black;
        }
        .inner {
            height: 75px;
            width: 50px;
            margin: 10px 12px;
            background-color: green;
        }
        
        .inner.changed {
            background-color: orange;
        }
    </style>
    <script>
        if (window.testRunner) {
            testRunner.dumpAsText();
            testRunner.waitUntilDone();
        }

        if (window.internals)
            internals.setPagination("LeftToRightPaginated", 0);

        function dumpLayers()
        {
            window.setTimeout(function() {
                if (window.internals)
                    internals.startTrackingRepaints();
                document.getElementById('inner').classList.add('changed');
                if (window.testRunner) {
                    document.getElementById('layers').innerText = window.internals.layerTreeAsText(document, internals.LAYER_TREE_INCLUDES_REPAINT_RECTS);
                    testRunner.notifyDone();
                }
            }, 10);
        }
        window.addEventListener('load', dumpLayers, false);
    </script>
</head>
<body>

    <div class="spacer"></div>
    <div class="spacer"></div>
    <div class="composited box">
        <div id="inner" class="inner box"></div>
    </div>

<pre id="layers">Layer tree goes here in DRT</pre>

</body>
</html>