chromium/third_party/blink/web_tests/external/wpt/speculation-rules/prerender/resources/cross-origin-iframe.html

<!DOCTYPE html>
<script src="/common/utils.js"></script>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="/common/get-host-info.sub.js"></script>
<script src="/speculation-rules/prerender/resources/utils.js"></script>
<script src="/speculation-rules/prerender/resources/deferred-promise-utils.js"></script>
<body>
<script>

async function main() {
  const crossOriginUrl =
      new URL('cross-origin-iframe-src.html',
              get_host_info()['HTTPS_REMOTE_ORIGIN'] +
                  window.location.pathname);

  // Start loading a cross-origin iframe. The iframe messages us with the
  // value of its document.prerendering, which should be false since load
  // is delayed until after activation.
  const crossOriginIframe = document.createElement('iframe');

  const gotMessage = new Promise((resolve, reject) => {
    window.addEventListener('message', (e) => {
     if (e.data == 'document.prerendering: false')
       resolve();
     else
       reject('bad message: ' + e.data);
    });
  });

  crossOriginIframe.src = crossOriginUrl.href;
  document.body.appendChild(crossOriginIframe);

  // To give the test a chance to fail by giving enough time if it loads the
  // cross-origin iframe instead of deferring, wait for a same-origin iframe to
  // load before proceeding with the test.
  await createFrame('empty.html');

  // Start the event collector to trigger activation.
  const prerenderEventCollector = new PrerenderEventCollector();
  prerenderEventCollector.start(gotMessage,
                                'iframe loaded');

}

// The main test page (cross-origin-iframe.https.html) loads the initiator
// page, then the initiator page will prerender itself with the
// `prerendering` parameter.
const params = new URLSearchParams(location.search);
if (!params.has('prerendering')) {
  const rule_extras = {'target_hint': getTargetHint()};
  loadInitiatorPage(rule_extras);
} else {
  main();
}
</script>
</body>