ServiceWorker: Modernize WPTs for Client.postMessage using async/await etc

This is a preparation for adding more tests for postMessage to worker clients.

Bug: n/a
Change-Id: I9e20b04fd86ad27faaecd7d592cac6dfa5ae16b1
Reviewed-on: https://chromium-review.googlesource.com/c/1317067
Commit-Queue: Hiroki Nakagawa <nhiroki@chromium.org>
Reviewed-by: Matt Falkenhagen <falken@chromium.org>
Cr-Commit-Position: refs/heads/master@{#605276}

third_party/WebKit/LayoutTests/external/wpt/service-workers/service-worker/postmessage-to-client.https.html

@@ -5,50 +5,38 @@
 <script src="/common/get-host-info.sub.js"></script>
 <script src="resources/test-helpers.sub.js"></script>
 <script>
-promise_test(t => {
-    var script = 'resources/postmessage-to-client-worker.js';
-    var scope = 'resources/blank.html';
-    var w;
+promise_test(async t => {
+  const script = 'resources/postmessage-to-client-worker.js';
+  const scope = 'resources/blank.html';
 
-    return service_worker_unregister_and_register(t, script, scope)
-      .then(registration => {
-          t.add_cleanup(() => registration.unregister());
-          return wait_for_state(t, registration.installing, 'activated');
-        })
-      .then(() => with_iframe(scope))
-      .then(frame => {
-          t.add_cleanup(() => frame.remove());
+  const registration =
+      await service_worker_unregister_and_register(t, script, scope);
+  t.add_cleanup(() => registration.unregister());
+  await wait_for_state(t, registration.installing, 'activated');
+  const frame = await with_iframe(scope);
+  t.add_cleanup(() => frame.remove());
+  const w = frame.contentWindow;
 
-          return new Promise(resolve => {
-              w = frame.contentWindow;
-              w.navigator.serviceWorker.onmessage = resolve;
-              w.navigator.serviceWorker.controller.postMessage('ping');
-            });
-        })
-      .then(e => {
-          var message = e.data;
-          assert_equals(e.constructor, w.MessageEvent,
-                        'message events should use MessageEvent interface.');
-          assert_equals(e.type, 'message', 'type should be "message".');
-          assert_equals(e.bubbles, false, 'message events should not bubble.');
-          assert_equals(e.cancelable, false,
-                        'message events should not be cancelable.');
-          assert_equals(
-              e.origin, location.origin,
-              'origin of message should be origin of Service Worker.');
-          assert_equals(e.lastEventId, '',
-                        'lastEventId should be an empty string.');
-          assert_equals(e.source.constructor, w.ServiceWorker,
-                        'source should use ServiceWorker interface.');
-          assert_equals(
-              e.source, w.navigator.serviceWorker.controller,
-              'source should be the service worker that sent the message.');
-          assert_equals(e.ports.length, 0, 'ports should be an empty array.');
-          assert_equals(message, 'Sending message via clients');
-          return new Promise(resolve => {
-              w.navigator.serviceWorker.onmessage = resolve;
-            });
-        })
-      .then(e => { assert_equals(e.data, 'quit'); });
-  }, 'postMessage from ServiceWorker to Client.');
+  w.navigator.serviceWorker.controller.postMessage('ping');
+  let e = await new Promise(r => w.navigator.serviceWorker.onmessage = r);
+
+  assert_equals(e.constructor, w.MessageEvent,
+                'message events should use MessageEvent interface.');
+  assert_equals(e.type, 'message', 'type should be "message".');
+  assert_false(e.bubbles, 'message events should not bubble.');
+  assert_false(e.cancelable, 'message events should not be cancelable.');
+  assert_equals(e.origin, location.origin,
+                'origin of message should be origin of Service Worker.');
+  assert_equals(e.lastEventId, '',
+                'lastEventId should be an empty string.');
+  assert_equals(e.source.constructor, w.ServiceWorker,
+                'source should use ServiceWorker interface.');
+  assert_equals(e.source, w.navigator.serviceWorker.controller,
+                'source should be the service worker that sent the message.');
+  assert_equals(e.ports.length, 0, 'ports should be an empty array.');
+  assert_equals(e.data, 'Sending message via clients');
+
+  e = await new Promise(r => w.navigator.serviceWorker.onmessage = r);
+  assert_equals(e.data, 'quit');
+}, 'postMessage from ServiceWorker to Client.');
 </script>