[Sync] Stop accessing BrowserContextKeyedServiceFactory on non-UI thread.

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 GenericChangeProcessor;
-class SyncClient;
+class SyncApiComponentFactory;
 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.
 // The GCP is created "on the fly" at just the right time, on just the right
 // thread. Given that, we use a factory to instantiate GenericChangeProcessors
 // so that tests can choose to use a fake processor (i.e instead of injection).
 // |sync_factory| is used to create AttachmentServicefor GenericChangeProcessor.
 // It is not retained after CreateGenericChangeProcessor exits.
 class GenericChangeProcessorFactory {
  public:
   GenericChangeProcessorFactory();
   virtual ~GenericChangeProcessorFactory();
   virtual std::unique_ptr<GenericChangeProcessor> CreateGenericChangeProcessor(
       ModelType type,
       UserShare* user_share,
       std::unique_ptr<DataTypeErrorHandler> error_handler,
       const base::WeakPtr<SyncableService>& local_service,
       const base::WeakPtr<SyncMergeResult>& merge_result,
-      SyncClient* sync_client);
+      SyncApiComponentFactory* driver_factory);
 
  private:
   DISALLOW_COPY_AND_ASSIGN(GenericChangeProcessorFactory);
 };
 
 }  // namespace syncer
 
 #endif  // COMPONENTS_SYNC_DRIVER_GENERIC_CHANGE_PROCESSOR_FACTORY_H_