Fix NotificationUIManagerTest::testShowAndCloseMultipleNotifications.

Do this by making sure that we don't unregister the Service Worker for
each notification that's being shown, which actually closes the existing
ones on the platform.

BUG=472926

Review URL: https://codereview.chromium.org/1082273003

Cr-Commit-Position: refs/heads/master@{#325436}

chrome/android/javatests/src/org/chromium/chrome/browser/notifications/NotificationUIManagerTest.java

@@ -13,7 +13,6 @@ import android.test.suitebuilder.annotation.SmallTest;
 
 import org.chromium.base.ThreadUtils;
 import org.chromium.base.annotations.SuppressFBWarnings;
-import org.chromium.base.test.util.DisabledTest;
 import org.chromium.base.test.util.Feature;
 import org.chromium.base.test.util.MinAndroidSdkLevel;
 import org.chromium.chrome.browser.preferences.website.ContentSetting;
@@ -292,12 +291,8 @@ public class NotificationUIManagerTest extends ChromeShellTestBase {
      * Verifies that multiple notifications without a tag can be opened and closed without
      * affecting eachother.
      */
-    /*
-    @MediumTest
+    @LargeTest
     @Feature({"Browser", "Notifications"})
-    crbug.com/472926
-    */
-    @DisabledTest
     public void testShowAndCloseMultipleNotifications() throws Exception {
         setNotificationContentSettingForCurrentOrigin(ContentSetting.ALLOW);
 

chrome/test/data/notifications/notification_test_utils.js

@@ -2,11 +2,15 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+var activatedServiceWorkerPromise = null;
+
 // Returns a promise that will be resolved with an activated Service
 // Worker, or rejects when the Service Worker could not be started. There
 // will be a message port to and from the worker in |messagePort|.
 function GetActivatedServiceWorker(script, scope) {
-  return navigator.serviceWorker.getRegistration(scope)
+  if (activatedServiceWorkerPromise == null) {
+    activatedServiceWorkerPromise =
+        navigator.serviceWorker.getRegistration(scope)
         .then(function(registration) {
           // Unregister any existing Service Worker.
           if (registration)
@@ -43,4 +47,7 @@ function GetActivatedServiceWorker(script, scope) {
             messagePort.start();
           });
         });
+  }
+
+  return activatedServiceWorkerPromise;
 }