Revert of [Sync] Make directory types registration explicit in ModelTypeRegistry

components/sync/driver/glue/sync_backend_host_impl.h

 // Copyright 2013 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_GLUE_SYNC_BACKEND_HOST_IMPL_H_
 #define COMPONENTS_SYNC_DRIVER_GLUE_SYNC_BACKEND_HOST_IMPL_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 42 matching lines @@
                       SyncClient* sync_client,
                       invalidation::InvalidationService* invalidator,
                       const base::WeakPtr<SyncPrefs>& sync_prefs,
                       const base::FilePath& sync_data_folder);
   ~SyncBackendHostImpl() override;
 
   // SyncEngine implementation.
   void Initialize(InitParams params) override;
   void TriggerRefresh(const ModelTypeSet& types) override;
   void UpdateCredentials(const SyncCredentials& credentials) override;
-  void StartConfiguration() override;
   void StartSyncingWithServer() override;
   void SetEncryptionPassphrase(const std::string& passphrase,
                                bool is_explicit) override;
   bool SetDecryptionPassphrase(const std::string& passphrase) override
       WARN_UNUSED_RESULT;
   void StopSyncingForShutdown() override;
   void Shutdown(ShutdownReason reason) override;
   void ConfigureDataTypes(ConfigureParams params) override;
-  void RegisterDirectoryDataType(ModelType type, ModelSafeGroup group) override;
-  void UnregisterDirectoryDataType(ModelType type) override;
   void ActivateDirectoryDataType(ModelType type,
                                  ModelSafeGroup group,
                                  ChangeProcessor* change_processor) override;
   void DeactivateDirectoryDataType(ModelType type) override;
   void ActivateNonBlockingDataType(ModelType type,
                                    std::unique_ptr<ActivationContext>) override;
   void DeactivateNonBlockingDataType(ModelType type) override;
   void EnableEncryptEverything() override;
   UserShare* GetUserShare() const override;
   Status GetDetailedStatus() override;
@@ skipping 214 matching lines @@
   base::ThreadChecker thread_checker_;
 
   base::WeakPtrFactory<SyncBackendHostImpl> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(SyncBackendHostImpl);
 };
 
 }  // namespace syncer
 
 #endif  // COMPONENTS_SYNC_DRIVER_GLUE_SYNC_BACKEND_HOST_IMPL_H_