Rename wm_core_export.h to wm_export.h and the wm_core target to just wm

ui/wm/core/transient_window_stacking_client.h

 // Copyright (c) 2013 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 UI_WM_CORE_TRANSIENT_WINDOW_STACKING_CLIENT_H_
 #define UI_WM_CORE_TRANSIENT_WINDOW_STACKING_CLIENT_H_
 
 #include "ui/aura/client/window_stacking_client.h"
-#include "ui/wm/core/wm_core_export.h"
+#include "ui/wm/wm_export.h"
 
 namespace wm {
 
 class TransientWindowManager;
 
-class WM_CORE_EXPORT TransientWindowStackingClient
+class WM_EXPORT TransientWindowStackingClient
     : public aura::client::WindowStackingClient {
  public:
   TransientWindowStackingClient();
   virtual ~TransientWindowStackingClient();
 
   // WindowStackingClient:
   virtual bool AdjustStacking(aura::Window** child,
                               aura::Window** target,
                               aura::Window::StackDirection* direction) OVERRIDE;
 
  private:
   // Purely for DCHECKs.
   friend class TransientWindowManager;
 
   static TransientWindowStackingClient* instance_;
 
   DISALLOW_COPY_AND_ASSIGN(TransientWindowStackingClient);
 };
 
 }  // namespace wm
 
 #endif  // UI_WM_CORE_TRANSIENT_WINDOW_STACKING_CLIENT_H_