chromium/third_party/blink/web_tests/http/tests/serviceworker/usecounter-on-load.html

<!DOCTYPE html>
<title>Service Worker: UseCounter for page controlled-on-load</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="resources/test-helpers.js"></script>
<script src="resources/usecounter.js"></script>
<script>

promise_test(function(t) {
    var url = 'resources/empty-worker.js';
    var scope = 'resources/blank.html?on-load';

    return service_worker_unregister_and_register(t, url, scope)
      .then(function(registration) {
          add_completion_callback(function() { registration.unregister(); });
          return wait_for_state(t, registration.installing, 'activated');
        })
      .then(function() { return with_iframe(scope) })
      .then(function(frame) {
          add_completion_callback(function() { frame.remove(); });
          var w = frame.contentWindow;
          var controller = w.navigator.serviceWorker.controller;
          assert_true(controller instanceof w.ServiceWorker);
          assert_true(isUseCounted(frame), 'should be counted as controlled');
        });
  }, 'usecounter is counted for a controlled document');

</script>
</html>