Revert of Remove header dependencies from sequence_checker.h to sequenced_worker_pool.h

components/history/core/browser/web_history_service.h

 // Copyright (c) 2012 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 COMPONENTS_HISTORY_CORE_BROWSER_WEB_HISTORY_SERVICE_H_
 #define COMPONENTS_HISTORY_CORE_BROWSER_WEB_HISTORY_SERVICE_H_
 
 #include <stddef.h>
 
 #include <map>
 #include <memory>
 #include <string>
 #include <vector>
 
-#include "base/callback_forward.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "base/observer_list.h"
 #include "components/history/core/browser/history_types.h"
 #include "components/keyed_service/core/keyed_service.h"
 
 namespace base {
 class DictionaryValue;
 }
@@ skipping 207 matching lines @@
   base::ObserverList<WebHistoryServiceObserver, true> observer_list_;
 
   base::WeakPtrFactory<WebHistoryService> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(WebHistoryService);
 };
 
 }  // namespace history
 
 #endif  // COMPONENTS_HISTORY_CORE_BROWSER_WEB_HISTORY_SERVICE_H_