Eliminate ash::internal namespace

ash/system/user/tray_user_separator.h

Index: ash/system/user/tray_user_separator.h
diff --git a/ash/system/user/tray_user_separator.h b/ash/system/user/tray_user_separator.h
index 62e52092d8aa29258165732cac30d8d0c5294538..003e4cd1d0828888509027c2849cdd1825dd0806 100644
--- a/ash/system/user/tray_user_separator.h
+++ b/ash/system/user/tray_user_separator.h
@@ -9,7 +9,6 @@
 #include "ash/system/tray/system_tray_item.h"
 
 namespace ash {
-namespace internal {
 
 // This tray item is showing an additional separator line between the logged in
 // users and the rest of the system tray menu. The separator will only be shown
@@ -41,7 +40,6 @@ class ASH_EXPORT TrayUserSeparator : public SystemTrayItem {
   DISALLOW_COPY_AND_ASSIGN(TrayUserSeparator);
 };
 
-}  // namespace internal
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_USER_TRAY_USER_SEPARATOR_H_