<!DOCTYPE html>

<html>
<head>
    <style>
        body {
            height: 5000px;
        }
        iframe {
            height: 400px;
            width: 800px;
            border: 5px solid black;
            box-shadow: 0 0 5px black;
            padding: 20px;
        }
    </style>
    <script>
        if (window.testRunner) {
            testRunner.dumpAsText();
            testRunner.waitUntilDone();
        }

        function doTest()
        {
            setTimeout(function() {
                window.scrollTo(0, 3000);
				internals.layerTreeAsText(subframe.contentDocument);
                if (window.internals) {
                    document.getElementById('layers').innerText = internals.layerTreeAsText(document,
                        internals.LAYER_TREE_INCLUDES_VISIBLE_RECTS | internals.LAYER_TREE_INCLUDES_TILE_CACHES);
                }
                if (window.testRunner)
                    testRunner.notifyDone();
            }, 0);
        }
        window.addEventListener('load', doTest, false);
    </script>
</head>
<body>

<iframe id="subframe" scrolling="no" srcdoc="<div style='width: 2500px; height: 200px; background-color: silver; will-change: transform'>Stuff here</div>"></iframe>
<pre id="layers">Layer tree goes here</p>
</body>
</html>