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

components/sync/driver/generic_change_processor_factory.h

Index: components/sync/driver/generic_change_processor_factory.h
diff --git a/components/sync/driver/generic_change_processor_factory.h b/components/sync/driver/generic_change_processor_factory.h
index 0d9d7c3d49ab8ba2f107592eb31551f4df836685..fbd82ad0f024c9a20fe80f7f5c29a2cb02ebd5b1 100644
--- a/components/sync/driver/generic_change_processor_factory.h
+++ b/components/sync/driver/generic_change_processor_factory.h
@@ -15,7 +15,7 @@
 namespace syncer {
 
 class GenericChangeProcessor;
-class SyncClient;
+class SyncApiComponentFactory;
 class SyncMergeResult;
 class SyncableService;
 struct UserShare;
@@ -39,7 +39,7 @@ class GenericChangeProcessorFactory {
       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);