[Sync] Register USS types with ModelTypeRegistry before download

components/sync_driver/fake_data_type_controller.h

Index: components/sync_driver/fake_data_type_controller.h
diff --git a/components/sync_driver/fake_data_type_controller.h b/components/sync_driver/fake_data_type_controller.h
index a08b61b494f324d8f3470f529c535f34511b6a02..0b84374e28783487812fc851937807fa1cf4a063 100644
--- a/components/sync_driver/fake_data_type_controller.h
+++ b/components/sync_driver/fake_data_type_controller.h
@@ -28,6 +28,7 @@ class FakeDataTypeController : public DirectoryDataTypeController {
   // DirectoryDataTypeController implementation.
   bool ShouldLoadModelBeforeConfigure() const override;
   void LoadModels(const ModelLoadCallback& model_load_callback) override;
+  void RegisterWithBackend(BackendDataTypeConfigurer* configurer) override;
   void StartAssociating(const StartCallback& start_callback) override;
   void Stop() override;
   syncer::ModelType type() const override;
@@ -51,6 +52,10 @@ class FakeDataTypeController : public DirectoryDataTypeController {
 
   void SetShouldLoadModelBeforeConfigure(bool value);
 
+  int register_with_backend_call_count() const {
+    return register_with_backend_call_count_;
+  }
+
  protected:
   ~FakeDataTypeController() override;
 
@@ -63,6 +68,7 @@ class FakeDataTypeController : public DirectoryDataTypeController {
   syncer::SyncError load_error_;
   bool ready_for_start_;
   bool should_load_model_before_configure_;
+  int register_with_backend_call_count_;
 };
 
 }  // namespace sync_driver