Eliminate ash::internal namespace

ash/system/tray/tray_notification_view.h

Index: ash/system/tray/tray_notification_view.h
diff --git a/ash/system/tray/tray_notification_view.h b/ash/system/tray/tray_notification_view.h
index 314b8aad7d2290af74b2159e087fa4b98f53b46f..28c2236ea13fad3534bda9afa597b5de112bf4b3 100644
--- a/ash/system/tray/tray_notification_view.h
+++ b/ash/system/tray/tray_notification_view.h
@@ -18,11 +18,8 @@ class ImageView;
 }
 
 namespace ash {
-
 class SystemTrayItem;
 
-namespace internal {
-
 // A view for closable notification views, laid out like:
 //  -------------------
 // | icon  contents  x |
@@ -92,7 +89,6 @@ class TrayNotificationView : public views::SlideOutView,
   DISALLOW_COPY_AND_ASSIGN(TrayNotificationView);
 };
 
-}  // namespace internal
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_TRAY_TRAY_NOTIFICATION_VIEW_H_