chromium/third_party/blink/web_tests/external/wpt/html/semantics/embedded-content/the-iframe-element/support/iframe_sandbox_026.htm

<!DOCTYPE html>
<html>
<head><title>Page with access to localStorage and sessionStorage</title>
</head>
<body>
    <script type="text/javascript">
        if (window.localStorage && window.sessionStorage) {
            parent.window.postMessage("access to window.localStorage and window.sessionStorage", "*");
        }
    </script>
</body>
</html>