chromium/third_party/blink/web_tests/external/wpt/fenced-frame/resources/resize-lock-inner.html

<!DOCTYPE html>
  <script src="utils.js"></script>
  <title>Fenced frame content to report any changes in inner dimensions</title>

  <body>
    <script>
      async function init() {
        const [resize_lock_inner_page_is_ready_key,
               resize_lock_resize_is_done_key,
               resize_lock_report_inner_dimensions_key] = parseKeylist();

        writeValueToServer(resize_lock_inner_page_is_ready_key, "ready");

        await nextValueFromServer(resize_lock_resize_is_done_key);

        const response = window.innerWidth + "x" + window.innerHeight;
        writeValueToServer(resize_lock_report_inner_dimensions_key, response);
      }

      init();
    </script>
  </body>
</html>