use-counter-third-party-controlled-iframe.html

<!DOCTYPE html>
<meta charset="utf-8">
<title>Controlled page</title>
<script>
// |kThirdPartyServiceWorker| from web_feature.mojom.
const kFeature = 3007;

window.onmessage = (async e => {
  if (e.data !== 'from_opener_assert_has_use_counter') {
    window.top.postMessage('FAIL: unexpected message', '*');
    return;
  }
  const registration = await navigator.serviceWorker.register('../resources/empty-worker.js');

  await window.internals.observeUseCounter(document, kFeature);
  if (window.internals.isUseCounted(document, kFeature)) {
    window.top.postMessage('from_iframe_verified_has_use_counter', '*');
    return;
  }

  window.top.postMessage('FAIL: !isUseCounted', '*');

  registration.unregister();
});
</script>

chromium/third_party/blink/web_tests/http/tests/serviceworker/resources/use-counter-third-party-controlled-iframe.html