Eliminate ash::internal namespace

ash/wm/workspace/workspace_event_handler.h

Index: ash/wm/workspace/workspace_event_handler.h
diff --git a/ash/wm/workspace/workspace_event_handler.h b/ash/wm/workspace/workspace_event_handler.h
index 65a05ac81d78a1326d5c6a3c1269f3810cdf63f8..f9498217207e99705a39be1f11105f3cefd79003 100644
--- a/ash/wm/workspace/workspace_event_handler.h
+++ b/ash/wm/workspace/workspace_event_handler.h
@@ -9,14 +9,12 @@
 #include "ui/events/event_handler.h"
 
 namespace ash {
+class WorkspaceEventHandlerTestHelper;
+
 namespace wm {
 class WindowState;
 }
 
-namespace internal {
-
-class WorkspaceEventHandlerTestHelper;
-
 class WorkspaceEventHandler : public ui::EventHandler {
  public:
   WorkspaceEventHandler();
@@ -41,7 +39,6 @@ class WorkspaceEventHandler : public ui::EventHandler {
   DISALLOW_COPY_AND_ASSIGN(WorkspaceEventHandler);
 };
 
-}  // namespace internal
 }  // namespace ash
 
 #endif  // ASH_WM_WORKSPACE_WORKSPACE_EVENT_HANDLER_H_