athena: Move athena_export.h into common/ directory.

athena/home/public/home_card.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_HOME_PUBLIC_HOME_CARD_H_
 #define ATHENA_HOME_PUBLIC_HOME_CARD_H_
 
-#include "athena/athena_export.h"
+#include "athena/common/athena_export.h"
 
 namespace app_list {
 class SearchProvider;
 }
 
 namespace athena {
 class AppModelBuilder;
 
 class ATHENA_EXPORT HomeCard {
  public:
   // Creates/deletes/gets the singleton object of the HomeCard
   // implementation. Takes the ownership of |model_builder|.
   static HomeCard* Create(AppModelBuilder* model_builder);
   static void Shutdown();
   static HomeCard* Get();
 
   virtual ~HomeCard() {}
 
   // Registers a search_provider to the HomeCard. Receiver will take
   // the ownership of the specified provider.
   virtual void RegisterSearchProvider(
       app_list::SearchProvider* search_provider) = 0;
 };
 
 }  // namespace athena
 
 #endif  // ATHENA_HOME_PUBLIC_HOME_CARD_H_