sync: Introduce ModelTypeRegistry and helpers

sync/internal_api/public/internal_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.
 //
 // An InternalComponentsFactory implementation designed for real production /
 // normal use.
 
 #ifndef SYNC_INTERNAL_API_PUBLIC_INTERNAL_COMPONENTS_FACTORY_IMPL_H_
 #define SYNC_INTERNAL_API_PUBLIC_INTERNAL_COMPONENTS_FACTORY_IMPL_H_
 
 #include "sync/base/sync_export.h"
 #include "sync/internal_api/public/internal_components_factory.h"
 
 namespace syncer {
 
 class SYNC_EXPORT InternalComponentsFactoryImpl
     : public InternalComponentsFactory {
  public:
   InternalComponentsFactoryImpl(const Switches& switches);
   virtual ~InternalComponentsFactoryImpl();
 
   virtual scoped_ptr<SyncScheduler> BuildScheduler(
       const std::string& name,
       sessions::SyncSessionContext* context,
       syncer::CancelationSignal* cancelation_signal) OVERRIDE;
 
   virtual scoped_ptr<sessions::SyncSessionContext> BuildContext(
       ServerConnectionManager* connection_manager,
       syncable::Directory* directory,
-      const std::vector<scoped_refptr<ModelSafeWorker> >& workers,
       ExtensionsActivity* extensions_activity,
       const std::vector<SyncEngineEventListener*>& listeners,
       sessions::DebugInfoGetter* debug_info_getter,
       TrafficRecorder* traffic_recorder,
+      ModelTypeRegistry* model_type_registry,
       const std::string& invalidator_client_id) OVERRIDE;
 
   virtual scoped_ptr<syncable::DirectoryBackingStore>
   BuildDirectoryBackingStore(
       const std::string& dir_name,
       const base::FilePath& backing_filepath) OVERRIDE;
 
   virtual Switches GetSwitches() const OVERRIDE;
 
  private:
   const Switches switches_;
   DISALLOW_COPY_AND_ASSIGN(InternalComponentsFactoryImpl);
 };
 
 }  // namespace syncer
 
 #endif  // SYNC_INTERNAL_API_PUBLIC_INTERNAL_COMPONENTS_FACTORY_IMPL_H_