Eliminate ash::internal namespace

ash/shelf/shelf_layout_manager.cc

Index: ash/shelf/shelf_layout_manager.cc
diff --git a/ash/shelf/shelf_layout_manager.cc b/ash/shelf/shelf_layout_manager.cc
index 8db87f4a02eeb3d202f47f5356bed1350505c6b4..c92c6f20fdc176008414430630f7c487faa20644 100644
--- a/ash/shelf/shelf_layout_manager.cc
+++ b/ash/shelf/shelf_layout_manager.cc
@@ -50,8 +50,6 @@
 #include "ui/wm/public/activation_client.h"
 
 namespace ash {
-namespace internal {
-
 namespace {
 
 // Delay before showing the shelf. This is after the mouse stops moving.
@@ -1184,5 +1182,4 @@ void ShelfLayoutManager::OnLockStateEvent(LockStateObserver::EventType event) {
   }
 }
 
-}  // namespace internal
 }  // namespace ash