chromium/third_party/blink/web_tests/http/tests/inspector-protocol/service-worker/resources/push-message-service-worker.html

<!DOCTYPE html>
<html>
<head>
<title>Service worker for a push message test</title>
<script>
function installSW() {
  navigator.serviceWorker.register('push-message-service-worker.js');
}

window.__messagePromise = new Promise(fulfill =>
    navigator.serviceWorker.onmessage = e => fulfill(e.data));

</script>
</head>
<body onload="installSW()"></body>
</html>