Initialize the message center as part of the testing browser process

chrome/browser/notifications/platform_notification_service_impl.cc

Index: chrome/browser/notifications/platform_notification_service_impl.cc
diff --git a/chrome/browser/notifications/platform_notification_service_impl.cc b/chrome/browser/notifications/platform_notification_service_impl.cc
index 2f79b35ba28726a7a4df6c89f2a6657713a91913..ea2e701225fe4cfa68c663fa54e6ce7f20427d05 100644
--- a/chrome/browser/notifications/platform_notification_service_impl.cc
+++ b/chrome/browser/notifications/platform_notification_service_impl.cc
@@ -367,8 +367,16 @@ bool PlatformNotificationServiceImpl::GetDisplayedPersistentNotifications(
   DCHECK(displayed_notifications);
 
   Profile* profile = Profile::FromBrowserContext(browser_context);
-  if (!profile || profile->AsTestingProfile())
-    return false;  // Tests will not have a message center.
+  if (!profile)
+    return false;
+
+  NotificationDisplayService* display_service =
+      GetNotificationDisplayService(profile);
+  if (!display_service) {
+    // Tests might not have a browser process
+    DCHECK(profile->AsTestingProfile());
+    return false;
+  }
 
   // TODO(peter): Filter for persistent notifications only.
   return GetNotificationDisplayService(profile)->GetDisplayed(