Initialize the message center as part of the testing browser process

chrome/browser/notifications/notification_display_service_factory.cc

Index: chrome/browser/notifications/notification_display_service_factory.cc
diff --git a/chrome/browser/notifications/notification_display_service_factory.cc b/chrome/browser/notifications/notification_display_service_factory.cc
index 8b40bcdab31544c9e5c7c2a0f2df89c79634622f..83a35a28d560000f627761c7e592e61f13c4b4e9 100644
--- a/chrome/browser/notifications/notification_display_service_factory.cc
+++ b/chrome/browser/notifications/notification_display_service_factory.cc
@@ -45,6 +45,10 @@ NotificationDisplayServiceFactory::NotificationDisplayServiceFactory()
 KeyedService* NotificationDisplayServiceFactory::BuildServiceInstanceFor(
     content::BrowserContext* context) const {
 #if defined(OS_ANDROID)
+  if (!g_browser_process->notification_platform_bridge()) {
+    DCHECK(Profile::FromBrowserContext(context)->AsTestingProfile());
+    return nullptr;
+  }
   return new NativeNotificationDisplayService(
       Profile::FromBrowserContext(context),
       g_browser_process->notification_platform_bridge());
@@ -55,6 +59,10 @@ KeyedService* NotificationDisplayServiceFactory::BuildServiceInstanceFor(
         g_browser_process->notification_platform_bridge());
   }
 #endif
+  if (!g_browser_process->notification_ui_manager()) {
+    DCHECK(Profile::FromBrowserContext(context)->AsTestingProfile());
+    return nullptr;
+  }
   return new MessageCenterDisplayService(
       Profile::FromBrowserContext(context),
       g_browser_process->notification_ui_manager());