Fixed Build breaks while notification is enabled and extension is disabled.

chrome/browser/notifications/desktop_notification_service.h

Index: chrome/browser/notifications/desktop_notification_service.h
diff --git a/chrome/browser/notifications/desktop_notification_service.h b/chrome/browser/notifications/desktop_notification_service.h
index ca71f572935e3bb6841c20a7dfbecbd2626cf105..61b7fde4c2f0c8edfa243ec3d889590871ede93b 100644
--- a/chrome/browser/notifications/desktop_notification_service.h
+++ b/chrome/browser/notifications/desktop_notification_service.h
@@ -58,9 +58,12 @@ typedef base::Callback<void(blink::WebNotificationPermission)>
 
 // The DesktopNotificationService is an object, owned by the Profile,
 // which provides the creation of desktop "toasts" to web pages and workers.
-class DesktopNotificationService
-    : public PermissionContextBase,
-      public extensions::ExtensionRegistryObserver {
+class DesktopNotificationService : public PermissionContextBase
+#if defined(ENABLE_EXTENSIONS)
+                                   ,
+                                   public extensions::ExtensionRegistryObserver
+#endif
+                                   {
  public:
   // Register profile-specific prefs of notifications.
   static void RegisterProfilePrefs(user_prefs::PrefRegistrySyncable* prefs);
@@ -130,11 +133,13 @@ class DesktopNotificationService
       const message_center::NotifierId& notifier_id,
       bool enabled);
 
+#if defined(ENABLE_EXTENSIONS)
   // extensions::ExtensionRegistryObserver:
   virtual void OnExtensionUninstalled(
       content::BrowserContext* browser_context,
       const extensions::Extension* extension,
       extensions::UninstallReason reason) OVERRIDE;
+#endif
 
   // The profile which owns this object.
   Profile* profile_;
@@ -151,10 +156,12 @@ class DesktopNotificationService
   // On-memory data for the availability of system_component.
   std::set<std::string> disabled_system_component_ids_;
 
+#if defined(ENABLE_EXTENSIONS)
   // An observer to listen when extension is uninstalled.
   ScopedObserver<extensions::ExtensionRegistry,
                  extensions::ExtensionRegistryObserver>
       extension_registry_observer_;
+#endif
 
   // Welcome Notification
   scoped_ptr<ExtensionWelcomeNotification> chrome_now_welcome_notification_;