components: Cleanup class/struct fwd declarations

components/sync/driver/generic_change_processor_factory.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 COMPONENTS_SYNC_DRIVER_GENERIC_CHANGE_PROCESSOR_FACTORY_H_
 #define COMPONENTS_SYNC_DRIVER_GENERIC_CHANGE_PROCESSOR_FACTORY_H_
 
 #include <memory>
 
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "components/sync/base/model_type.h"
 #include "components/sync/model/data_type_error_handler.h"
 
 namespace syncer {
 
-class AttachmentService;
 class GenericChangeProcessor;
 class SyncClient;
 class SyncMergeResult;
 class SyncableService;
 struct UserShare;
 
 // Because GenericChangeProcessors are created and used only from the model
 // thread, their lifetime is strictly shorter than other components like
 // DataTypeController, which live before / after communication with model
 // threads begins and ends.
@@ skipping 14 matching lines @@
       const base::WeakPtr<SyncMergeResult>& merge_result,
       SyncClient* sync_client);
 
  private:
   DISALLOW_COPY_AND_ASSIGN(GenericChangeProcessorFactory);
 };
 
 }  // namespace syncer
 
 #endif  // COMPONENTS_SYNC_DRIVER_GENERIC_CHANGE_PROCESSOR_FACTORY_H_