Eliminate ash::internal namespace

ash/system/chromeos/session/tray_session_length_limit.h

Index: ash/system/chromeos/session/tray_session_length_limit.h
diff --git a/ash/system/chromeos/session/tray_session_length_limit.h b/ash/system/chromeos/session/tray_session_length_limit.h
index 5b31cbb2819cff4bd8ee99cec38a09201d12346f..1c9da1713659256d007e540081e98424c79af473 100644
--- a/ash/system/chromeos/session/tray_session_length_limit.h
+++ b/ash/system/chromeos/session/tray_session_length_limit.h
@@ -14,13 +14,10 @@
 #include "base/timer/timer.h"
 
 namespace ash {
-
 namespace test {
 class TraySessionLengthLimitTest;
 }
 
-namespace internal {
-
 namespace tray {
 class RemainingSessionTimeTrayView;
 }
@@ -71,7 +68,6 @@ class ASH_EXPORT TraySessionLengthLimit : public SystemTrayItem,
   DISALLOW_COPY_AND_ASSIGN(TraySessionLengthLimit);
 };
 
-}  // namespace internal
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_CHROMEOS_SESSION_SESSION_LENGTH_LIMIT_H_