Support persistent notifications in the PlatformNotificationServiceImpl.

chrome/chrome_tests.gypi

Index: chrome/chrome_tests.gypi
diff --git a/chrome/chrome_tests.gypi b/chrome/chrome_tests.gypi
index 0d21c411a64ac07667fc85246e5bf85340a16709..db9236c1ccd10a80ea2dd0c945a156b0353c47c0 100644
--- a/chrome/chrome_tests.gypi
+++ b/chrome/chrome_tests.gypi
@@ -1478,6 +1478,7 @@
               # cross-platform panels).
               'sources': [
                 'browser/notifications/notification_browsertest.cc',
+                'browser/notifications/platform_notification_service_browsertest.cc',
               ],
             }],
           ],
@@ -1489,6 +1490,7 @@
 
             # TODO(peter): Enable the Notification browser tests.
             'browser/notifications/notification_browsertest.cc',
+            'browser/notifications/platform_notification_service_browsertest.cc',
           ]
         }],
         ['toolkit_views==1', {