Eliminate ash::internal namespace

ash/shelf/shelf_window_watcher.cc

Index: ash/shelf/shelf_window_watcher.cc
diff --git a/ash/shelf/shelf_window_watcher.cc b/ash/shelf/shelf_window_watcher.cc
index 9488d10d031224f2562c0a1d9ae0cc83e60ed07d..b16deeaf283c2265f703688079290a77db261c6b 100644
--- a/ash/shelf/shelf_window_watcher.cc
+++ b/ash/shelf/shelf_window_watcher.cc
@@ -50,7 +50,6 @@ bool IsDragging(aura::Window* window) {
 }  // namespace
 
 namespace ash {
-namespace internal {
 
 ShelfWindowWatcher::RootWindowObserver::RootWindowObserver(
     ShelfWindowWatcher* window_watcher)
@@ -289,5 +288,4 @@ void ShelfWindowWatcher::OnDisplayRemoved(const gfx::Display& old_display) {
   // Do nothing here.
 }
 
-}  // namespace internal
 }  // namespace ash