ExtensionApiTest.Notifications: wait until part 1 finishes cleanup before going to part 2

chrome/test/data/extensions/api_test/notifications/has_permission_prefs/background.html

 <script>
 var notification = null;
 
 // Shows the notification window using the specified URL.
 // Control continues at onNotificationDone().
 function showNotification(url) {
   notification = window.webkitNotifications.createHTMLNotification(url);
   notification.onerror = function() {
     chrome.test.fail("Failed to show notification.");
   };
   notification.show();
 }
 
 // Called by the notification when it is done with its tests.
-function onNotificationDone() {
+function onNotificationDone(notificationWindow) {
   var views = chrome.extension.getViews();
   chrome.test.assertEq(2, views.length);
+  notificationWindow.onunload = function() {
+    chrome.test.succeed();
+  }
   notification.cancel();
-  chrome.test.succeed();
 }
 
 chrome.test.runTests([
   function hasPermission() {
     chrome.test.assertEq(0,  // allowed
                          webkitNotifications.checkPermission());
     chrome.test.succeed();
   },
   function absoluteURL() {
     showNotification(chrome.extension.getURL("notification.html"));
   },
   function relativeURL() {
     showNotification("notification.html");
   }
 ]);
 </script>