Eliminate ash::internal namespace

ash/system/bluetooth/tray_bluetooth.h

Index: ash/system/bluetooth/tray_bluetooth.h
diff --git a/ash/system/bluetooth/tray_bluetooth.h b/ash/system/bluetooth/tray_bluetooth.h
index 2e452c643d971998726b9cb5924e1454540b8c80..1330c3c299edf151b947d16e9edf991fbf8fb2b1 100644
--- a/ash/system/bluetooth/tray_bluetooth.h
+++ b/ash/system/bluetooth/tray_bluetooth.h
@@ -9,8 +9,6 @@
 #include "ash/system/tray/system_tray_item.h"
 
 namespace ash {
-namespace internal {
-
 namespace tray {
 class BluetoothDefaultView;
 class BluetoothDetailedView;
@@ -42,7 +40,6 @@ class TrayBluetooth : public SystemTrayItem,
   DISALLOW_COPY_AND_ASSIGN(TrayBluetooth);
 };
 
-}  // namespace internal
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_BLUETOOTH_TRAY_BLUETOOTH_H_