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

components/sync_driver/directory_data_type_controller.h

Index: components/sync_driver/directory_data_type_controller.h
diff --git a/components/sync_driver/directory_data_type_controller.h b/components/sync_driver/directory_data_type_controller.h
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+++ b/components/sync_driver/directory_data_type_controller.h
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+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef COMPONENTS_SYNC_DRIVER_DIRECTORY_DATA_TYPE_CONTROLLER_H__
+#define COMPONENTS_SYNC_DRIVER_DIRECTORY_DATA_TYPE_CONTROLLER_H__
+
+#include "components/sync_driver/data_type_controller.h"
+
+#include "sync/internal_api/public/engine/model_safe_worker.h"
+
+namespace sync_driver {
+class ChangeProcessor;
+
+// Base class for Directory based Data type controllers.
+class DirectoryDataTypeController : public DataTypeController {
+ public:
+  // Directory specific implementation of ActivateDataType with the
+  // type specific ChangeProcessor and ModelSafeGroup.
+  // Activates change processing on the controlled data type.
+  // This is called by DataTypeManager, synchronously with data type's
+  // model association.
+  // See BackendDataTypeConfigurer::ActivateDataType for more details.
+  void ActivateDataType(BackendDataTypeConfigurer* configurer) override;
+
+  // Directory specific implementation of DeactivateDataType.
+  // Deactivates change processing on the controlled data type (by removing
+  // the data type's ChangeProcessor registration with the backend).
+  // See BackendDataTypeConfigurer::DeactivateDataType for more details.
+  void DeactivateDataType(BackendDataTypeConfigurer* configurer) override;
+
+ protected:
+  // The model safe group of this data type.  This should reflect the
+  // thread that should be used to modify the data type's native
+  // model.
+  virtual syncer::ModelSafeGroup model_safe_group() const = 0;
+
+  // Access to the ChangeProcessor for the type being controlled by |this|.
+  // Returns NULL if the ChangeProcessor isn't created or connected.
+  virtual ChangeProcessor* GetChangeProcessor() const = 0;
+
+  DirectoryDataTypeController(
+      const scoped_refptr<base::SingleThreadTaskRunner>& ui_thread,
+      const base::Closure& error_callback);
+
+  ~DirectoryDataTypeController() override;
+};
+
+}  // namespace sync_driver
+
+#endif  // COMPONENTS_SYNC_DRIVER_DIRECTORY_DATA_TYPE_CONTROLLER_H__