Eliminate ash::internal namespace

ash/system/tray/tray_event_filter.h

Index: ash/system/tray/tray_event_filter.h
diff --git a/ash/system/tray/tray_event_filter.h b/ash/system/tray/tray_event_filter.h
index 40593155c2c932de1b35dbb5e11c3e0342795791..e77e00f9f8de3191f8f6b2d10e0fc466a19ddc60 100644
--- a/ash/system/tray/tray_event_filter.h
+++ b/ash/system/tray/tray_event_filter.h
@@ -16,8 +16,6 @@ class Window;
 }
 
 namespace ash {
-namespace internal {
-
 class TrayBubbleWrapper;
 
 // Handles events for a tray bubble.
@@ -43,7 +41,6 @@ class TrayEventFilter : public ui::EventHandler {
   DISALLOW_COPY_AND_ASSIGN(TrayEventFilter);
 };
 
-}  // namespace internal
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_TRAY_TRAY_EVENT_FILTER_H_