ash: Cleanup class/struct forward declarations

ash/common/wm/drag_details.h

 // Copyright 2014 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_COMMON_WM_DRAG_DETAILS_H_
 #define ASH_COMMON_WM_DRAG_DETAILS_H_
 
 #include "ash/ash_export.h"
 #include "ash/common/wm/wm_types.h"
 #include "ui/gfx/geometry/rect.h"
 #include "ui/wm/public/window_move_client.h"
 
-namespace aura {
-class Window;
-}
-
 namespace ash {
 
 class WmWindow;
 
-namespace wm {
-class WindowState;
-}
-
 struct ASH_EXPORT DragDetails {
   DragDetails(WmWindow* window,
               const gfx::Point& location,
               int window_component,
               // TODO(sky): make wm type.
               aura::client::WindowMoveSource source);
   ~DragDetails();
 
   ash::wm::WindowStateType initial_state_type;
 
@@ skipping 28 matching lines @@
   // Source of the event initiating the drag.
   const aura::client::WindowMoveSource source;
 
   // True if the window should attach to the shelf after releasing.
   bool should_attach_to_shelf;
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_WM_DRAG_DETAILS_H_