chromium/third_party/blink/web_tests/fast/events/resources/modal-dialog.html

<html>
<head>
<script>
    function closeWindow()
    {
        if (window.testRunner) {
            testRunner.notifyDone();
        }
        opener.log("Modal dialog closing.");
        if (window.testRunner) {
            testRunner.abortModal();
        }
        close();
    }
</script>
</head>

<body onload="closeWindow()">
    This is a modal dialog.
</body>
</html>