components: Cleanup class/struct fwd declarations

components/webdata/common/web_database_service.h

 // Copyright 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.
 
 // Chromium settings and storage represent user-selected preferences and
 // information and MUST not be extracted, overwritten or modified except
 // through Chromium defined APIs.
 
 #ifndef COMPONENTS_WEBDATA_COMMON_WEB_DATABASE_SERVICE_H_
 #define COMPONENTS_WEBDATA_COMMON_WEB_DATABASE_SERVICE_H_
 
 #include <memory>
 
 #include "base/callback_forward.h"
 #include "base/compiler_specific.h"
 #include "base/files/file_path.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/ref_counted_delete_on_message_loop.h"
 #include "base/memory/weak_ptr.h"
 #include "base/observer_list.h"
 #include "base/single_thread_task_runner.h"
 #include "components/webdata/common/web_data_service_base.h"
 #include "components/webdata/common/web_database.h"
 #include "components/webdata/common/webdata_export.h"
 
 class WebDatabaseBackend;
-class WebDataRequestManager;
-
-namespace content {
-class BrowserContext;
-}
 
 namespace tracked_objects {
 class Location;
 }
 
 class WDTypedResult;
 class WebDataServiceConsumer;
 
 
 ////////////////////////////////////////////////////////////////////////////////
@@ skipping 102 matching lines @@
 
   scoped_refptr<base::SingleThreadTaskRunner> db_thread_;
 
   // All vended weak pointers are invalidated in ShutdownDatabase().
   base::WeakPtrFactory<WebDatabaseService> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(WebDatabaseService);
 };
 
 #endif  // COMPONENTS_WEBDATA_COMMON_WEB_DATABASE_SERVICE_H_