athena: Move athena_export.h into common/ directory.

athena/screen/public/screen_manager.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 ATHENA_SCREEN_PUBLIC_SCREEN_MANAGER_H_
 #define ATHENA_SCREEN_PUBLIC_SCREEN_MANAGER_H_
 
 #include <string>
 
-#include "athena/athena_export.h"
+#include "athena/common/athena_export.h"
 
 namespace aura {
 class Window;
 }
 
 namespace gfx {
 class ImageSkia;
 }
 
 namespace athena {
@@ skipping 21 matching lines @@
   // Return the context object to be used for widget creation.
   virtual aura::Window* GetContext() = 0;
 
   // Sets the background image.
   virtual void SetBackgroundImage(const gfx::ImageSkia& image) = 0;
 };
 
 }  // namespace athena
 
 #endif  // ATHENA_SCREEN_PUBLIC_SCREEN_MANAGER_H_