ash: Cleanup class/struct forward declarations

ash/mus/root_window_controller.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef ASH_MUS_ROOT_WINDOW_CONTROLLER_H_
 #define ASH_MUS_ROOT_WINDOW_CONTROLLER_H_
 
 #include <memory>
 
 #include "ash/mus/disconnected_app_handler.h"
 #include "services/ui/public/cpp/window_observer.h"
 #include "services/ui/public/interfaces/window_manager_constants.mojom.h"
 #include "ui/display/display.h"
 
 namespace gfx {
 class Insets;
 }
 
 namespace service_manager {
 class Connector;
 }
 
 namespace ash {
 
-class WorkspaceLayoutManager;
-
 namespace mus {
 
 class LayoutManager;
 class WindowManager;
 class WmRootWindowControllerMus;
 class WmShelfMus;
 class WmTestBase;
 class WmTestHelper;
 class WmWindowMus;
 
@@ skipping 52 matching lines @@
 
   std::unique_ptr<DisconnectedAppHandler> disconnected_app_handler_;
 
   DISALLOW_COPY_AND_ASSIGN(RootWindowController);
 };
 
 }  // namespace mus
 }  // namespace ash
 
 #endif  // ASH_MUS_ROOT_WINDOW_CONTROLLER_H_