Discard unused AppListPrefs code.

chrome/browser/ui/app_list/app_list_syncable_service.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 CHROME_BROWSER_UI_APP_LIST_APP_LIST_SYNCABLE_SERVICE_H_
 #define CHROME_BROWSER_UI_APP_LIST_APP_LIST_SYNCABLE_SERVICE_H_
 
 #include <stddef.h>
 
 #include <map>
@@ skipping 26 matching lines @@
 
 namespace sync_pb {
 class AppListSpecifics;
 }
 
 namespace app_list {
 
 class AppListFolderItem;
 class AppListItem;
 class AppListModel;
-class ModelPrefUpdater;
 
 // Keyed Service that owns, stores, and syncs an AppListModel for a profile.
 class AppListSyncableService : public syncer::SyncableService,
                                public KeyedService,
                                public DriveAppUninstallSyncService {
  public:
   struct SyncItem {
     SyncItem(const std::string& id,
              sync_pb::AppListSpecifics::AppListItemType type);
     ~SyncItem();
@@ skipping 172 matching lines @@
   // an OEM (extension->was_installed_by_oem() is true).
   bool AppIsOem(const std::string& id);
 
   // Helper that notifies observers that sync model has been updated.
   void NotifyObserversSyncUpdated();
 
   Profile* profile_;
   extensions::ExtensionSystem* extension_system_;
   std::unique_ptr<AppListModel> model_;
   std::unique_ptr<ModelObserver> model_observer_;
-  std::unique_ptr<ModelPrefUpdater> model_pref_updater_;
   std::unique_ptr<ExtensionAppModelBuilder> apps_builder_;
 #if defined(OS_CHROMEOS)
   std::unique_ptr<ArcAppModelBuilder> arc_apps_builder_;
 #endif
   std::unique_ptr<syncer::SyncChangeProcessor> sync_processor_;
   std::unique_ptr<syncer::SyncErrorFactory> sync_error_handler_;
   SyncItemMap sync_items_;
   syncer::SyncableService::StartSyncFlare flare_;
   bool initial_sync_data_processed_;
   bool first_app_list_sync_;
   std::string oem_folder_name_;
 
   // List of observers.
   base::ObserverList<Observer> observer_list_;
 
   // Provides integration with Drive apps.
   std::unique_ptr<DriveAppProvider> drive_app_provider_;
 
   DISALLOW_COPY_AND_ASSIGN(AppListSyncableService);
 };
 
 }  // namespace app_list
 
 #endif  // CHROME_BROWSER_UI_APP_LIST_APP_LIST_SYNCABLE_SERVICE_H_