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

components/sync/engine/engine_components_factory_impl.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_IMPL_H_
 #define COMPONENTS_SYNC_ENGINE_ENGINE_COMPONENTS_FACTORY_IMPL_H_
 
 #include <memory>
 #include <string>
 #include <vector>
 
 #include "base/macros.h"
 #include "components/sync/engine/engine_components_factory.h"
 
 namespace syncer {
 
 // An EngineComponentsFactory implementation designed for real production /
 // normal use.
 class EngineComponentsFactoryImpl : public EngineComponentsFactory {
  public:
   explicit EngineComponentsFactoryImpl(const Switches& switches);
   ~EngineComponentsFactoryImpl() override;
 
   std::unique_ptr<SyncScheduler> BuildScheduler(
       const std::string& name,
       SyncCycleContext* context,
-      CancelationSignal* cancelation_signal) override;
+      CancelationSignal* cancelation_signal,
+      bool ignore_auth_credentials) override;
 
   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) override;
 
   std::unique_ptr<syncable::DirectoryBackingStore> BuildDirectoryBackingStore(
       StorageOption storage,
       const std::string& dir_name,
       const base::FilePath& backing_filepath) override;
 
   Switches GetSwitches() const override;
 
  private:
   const Switches switches_;
   DISALLOW_COPY_AND_ASSIGN(EngineComponentsFactoryImpl);
 };
 
 }  // namespace syncer
 
 #endif  // COMPONENTS_SYNC_ENGINE_ENGINE_COMPONENTS_FACTORY_IMPL_H_