chromium/chrome/test/data/prerender/onprerendering_check.html

<!DOCTYPE html>
<html>
<head>
<script>
// Records if 'onprerenderingchange' event is triggered at least once.
const onprerenderingchange_observed_promise = new Promise(resolve => {
  document.addEventListener('prerenderingchange', () => {
    resolve(true);
  });
});
</script>
</head>
</html>