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

components/sync/driver/generic_change_processor_factory.cc

Index: components/sync/driver/generic_change_processor_factory.cc
diff --git a/components/sync/driver/generic_change_processor_factory.cc b/components/sync/driver/generic_change_processor_factory.cc
index 02ff37a1d08cffd4b2ddbecfd76c9350f5c4cdce..bfb268b0560ca234606a7bad0f692aac38ab091a 100644
--- a/components/sync/driver/generic_change_processor_factory.cc
+++ b/components/sync/driver/generic_change_processor_factory.cc
@@ -23,11 +23,11 @@
     std::unique_ptr<DataTypeErrorHandler> error_handler,
     const base::WeakPtr<SyncableService>& local_service,
     const base::WeakPtr<SyncMergeResult>& merge_result,
-    SyncApiComponentFactory* driver_factory) {
+    SyncClient* sync_client) {
   DCHECK(user_share);
   return base::MakeUnique<GenericChangeProcessor>(
       type, std::move(error_handler), local_service, merge_result, user_share,
-      driver_factory, local_service->GetAttachmentStoreForSync());
+      sync_client, local_service->GetAttachmentStoreForSync());
 }
 
 }  // namespace syncer