[Sync] Allow sync start without sign-in if the local sync backend is on.

components/sync/engine/engine_components_factory.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_ENGINE_COMPONENTS_FACTORY_H_
 #define COMPONENTS_SYNC_ENGINE_ENGINE_COMPONENTS_FACTORY_H_
 
 #include <memory>
 #include <string>
 #include <vector>
@@ skipping 72 matching lines @@
     STORAGE_ON_DISK,
     // Use this to test the case where a directory fails to load.
     STORAGE_INVALID
   };
 
   virtual ~EngineComponentsFactory() {}
 
   virtual std::unique_ptr<SyncScheduler> BuildScheduler(
       const std::string& name,
       SyncCycleContext* context,
-      CancelationSignal* cancelation_signal) = 0;
+      CancelationSignal* cancelation_signal,
+      bool ignore_auth_credentials) = 0;
 
   virtual std::unique_ptr<SyncCycleContext> BuildContext(
       ServerConnectionManager* connection_manager,
       syncable::Directory* directory,
       ExtensionsActivity* extensions_activity,
       const std::vector<SyncEngineEventListener*>& listeners,
       DebugInfoGetter* debug_info_getter,
       ModelTypeRegistry* model_type_registry,
       const std::string& invalidator_client_id) = 0;
 
   virtual std::unique_ptr<syncable::DirectoryBackingStore>
   BuildDirectoryBackingStore(StorageOption storage,
                              const std::string& dir_name,
                              const base::FilePath& backing_filepath) = 0;
 
   // Returns the Switches struct that this object is using as configuration, if
   // the implementation is making use of one.
   virtual Switches GetSwitches() const = 0;
 };
 
 }  // namespace syncer
 
 #endif  // COMPONENTS_SYNC_ENGINE_ENGINE_COMPONENTS_FACTORY_H_