speculation-rules/prerender/resources/web-locks.html

<!DOCTYPE html>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="/speculation-rules/prerender/resources/utils.js"></script>
<script src="/speculation-rules/prerender/resources/deferred-promise-utils.js"></script>
<script>

const params = new URLSearchParams(location.search);

// The main test page (restriction-web-locks.html) loads the initiator page,
// then the initiator page will prerender itself with the `prerendering`
// parameter.
const isPrerendering = params.has('prerendering');

if (!isPrerendering) {
  loadInitiatorPage();
} else {
  const method = params.get('method');
  const prerenderEventCollector = new PrerenderEventCollector();
  let promise;
  switch(method) {
    case 'request':
      promise = navigator.locks.request('prerender-test-lock', lock => {});
      break;
    case 'query':
      promise = navigator.locks.query();
      break;
  }
  prerenderEventCollector.start(promise, `navigator.locks.${method}`);
}

</script>