chromium/third_party/blink/web_tests/external/wpt/service-workers/service-worker/data-iframe.html

<!DOCTYPE html>
<title>Service Workers in data iframes</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="resources/test-helpers.sub.js"></script>
<body></body>
<script>
'use strict';

promise_test(t => {
  const url = encodeURI(`data:text/html,<!DOCTYPE html>
  <script>
    parent.postMessage({ isDefined: 'serviceWorker' in navigator }, '*');
  </` + `script>`);
  var p = new Promise((resolve, reject) => {
    window.addEventListener('message', event => {
      resolve(event.data.isDefined);
    });
  });
  with_iframe(url);
  return p.then(isDefined => {
    assert_false(isDefined, 'navigator.serviceWorker should not be defined in iframe');
  });
}, 'navigator.serviceWorker is not available in a data: iframe');
</script>