[Sync] Adding storage key concept for ModelTypeServices.

components/sync/api/fake_model_type_service.cc

Index: components/sync/api/fake_model_type_service.cc
diff --git a/components/sync/api/fake_model_type_service.cc b/components/sync/api/fake_model_type_service.cc
index 82ec3d710da9054b0db4b72226a773f5840eb095..aff736289e4ec5002a24316701bc5f9c5b8132b7 100644
--- a/components/sync/api/fake_model_type_service.cc
+++ b/components/sync/api/fake_model_type_service.cc
@@ -38,7 +38,7 @@ syncer::SyncError FakeModelTypeService::ApplySyncChanges(
   return syncer::SyncError();
 }
 
-void FakeModelTypeService::GetData(ClientTagList client_tags,
+void FakeModelTypeService::GetData(StorageKeyList storage_keys,
                                    DataCallback callback) {}
 
 void FakeModelTypeService::GetAllData(DataCallback callback) {}
@@ -47,6 +47,10 @@ std::string FakeModelTypeService::GetClientTag(const EntityData& entity_data) {
   return std::string();
 }
 
+std::string FakeModelTypeService::GetStorageKey(const EntityData& entity_data) {
+  return std::string();
+}
+
 void FakeModelTypeService::OnChangeProcessorSet() {}
 
 bool FakeModelTypeService::HasChangeProcessor() const {