Sync: Refactoring DataTypeController to make the design shareable with USS datatypes.

components/sync_driver/proxy_data_type_controller.h

Index: components/sync_driver/proxy_data_type_controller.h
diff --git a/components/sync_driver/proxy_data_type_controller.h b/components/sync_driver/proxy_data_type_controller.h
index 97a49e5302bd25699fb801cb30f5aa36192ce62f..d0f249ef68e3178b5e67d8a10ee6f697db86fe83 100644
--- a/components/sync_driver/proxy_data_type_controller.h
+++ b/components/sync_driver/proxy_data_type_controller.h
@@ -26,10 +26,10 @@ class ProxyDataTypeController : public DataTypeController {
   void StartAssociating(const StartCallback& start_callback) override;
   void Stop() override;
   syncer::ModelType type() const override;
-  syncer::ModelSafeGroup model_safe_group() const override;
-  ChangeProcessor* GetChangeProcessor() const override;
   std::string name() const override;
   State state() const override;
+  void ActivateDataType(BackendDataTypeConfigurer* configurer) override;
+  void DeactivateDataType(BackendDataTypeConfigurer* configurer) override;
 
   // DataTypeErrorHandler interface.
   void OnSingleDataTypeUnrecoverableError(