chromium/third_party/blink/web_tests/external/wpt/fenced-frame/resources/window-outer-dimensions-inner.html

<!DOCTYPE html>
<script src="utils.js"></script>
<title>Fenced frame content to report the result of prerendering</title>

<body>
  <script>
    async function report() { // Needed in order to use top-level await.
      // This file is meant to run in a <fencedframe>. It reports its dimensions
      // back to the outermost page, which in turn checks for correctness.
      const [window_outer_size_key, window_inner_size_key, dimension,
             extra_children] = parseKeylist();

      const url = new URL(location.href);

      if (extra_children == "0") {
        let outer_result = (dimension == "width") ?
          window.outerWidth : window.outerHeight;

        let inner_result = (dimension == "width") ?
          window.innerWidth : window.innerHeight;

        writeValueToServer(window_outer_size_key, outer_result);
        writeValueToServer(window_inner_size_key, inner_result);
      } else {
          const iframe = document.createElement('iframe');
          const frame_url = generateURL('window-outer-dimensions-inner.html',
            [window_outer_size_key, window_inner_size_key, dimension,
            (parseInt(extra_children) - 1)]);
          iframe.src = frame_url;
          document.body.append(iframe);
      }

    }
    report();
  </script>
</body>