[Sync] Make directory types registration explicit in ModelTypeRegistry

components/sync/engine/sync_engine.h

 // Copyright 2012 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_ENGINE_SYNC_ENGINE_H_
 #define COMPONENTS_SYNC_ENGINE_SYNC_ENGINE_H_
 
 #include <map>
 #include <memory>
 #include <string>
@@ skipping 77 matching lines @@
   // |saved_nigori_state| is optional nigori state to restore from a previous
   // engine instance. May be null.
   virtual void Initialize(InitParams params) = 0;
 
   // Inform the engine to trigger a sync cycle for |types|.
   virtual void TriggerRefresh(const ModelTypeSet& types) = 0;
 
   // Updates the engine's SyncCredentials.
   virtual void UpdateCredentials(const SyncCredentials& credentials) = 0;
 
+  // Switches sync engine into configuration mode. In this mode only initial
+  // data for newly enabled types is downloaded from server. No local changes
+  // are committed to server.
+  virtual void StartConfiguration() = 0;
+
   // This starts the sync engine running a Syncer object to communicate with
   // sync servers. Until this is called, no changes will leave or enter this
   // browser from the cloud / sync servers.
   virtual void StartSyncingWithServer() = 0;
 
   // Asynchronously set a new passphrase for encryption. Note that it is an
   // error to call SetEncryptionPassphrase under the following circumstances:
   // - An explicit passphrase has already been set
   // - |is_explicit| is true and we have pending keys.
   // When |is_explicit| is false, a couple of things could happen:
@@ skipping 88 matching lines @@
   // See SyncManager::OnCookieJarChanged.
   virtual void OnCookieJarChanged(bool account_mismatch, bool empty_jar) = 0;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(SyncEngine);
 };
 
 }  // namespace syncer
 
 #endif  // COMPONENTS_SYNC_ENGINE_SYNC_ENGINE_H_