Implement local storage for App List in case app sync is off.

chrome/browser/ui/app_list/app_list_syncable_service.h

Index: chrome/browser/ui/app_list/app_list_syncable_service.h
diff --git a/chrome/browser/ui/app_list/app_list_syncable_service.h b/chrome/browser/ui/app_list/app_list_syncable_service.h
index 7900f3f664833b85aa6288a0a3d50d218c706599..87fc3f4917bcc8b65b89f5005dd2858363b42b0d 100644
--- a/chrome/browser/ui/app_list/app_list_syncable_service.h
+++ b/chrome/browser/ui/app_list/app_list_syncable_service.h
@@ -11,6 +11,7 @@
 #include <memory>
 
 #include "base/macros.h"
+#include "base/memory/weak_ptr.h"
 #include "base/observer_list.h"
 #include "build/build_config.h"
 #include "chrome/browser/apps/drive/drive_app_uninstall_sync_service.h"
@@ -39,6 +40,10 @@ namespace sync_pb {
 class AppListSpecifics;
 }
 
+namespace user_prefs {
+class PrefRegistrySyncable;
+}
+
 namespace app_list {
 
 class AppListFolderItem;
@@ -81,6 +86,9 @@ class AppListSyncableService : public syncer::SyncableService,
 
   ~AppListSyncableService() override;
 
+  // Registers prefs to support local storage.
+  static void RegisterProfilePrefs(user_prefs::PrefRegistrySyncable* registry);
+
   // Adds |item| to |sync_items_| and |model_|. If a sync item already exists,
   // updates the existing sync item instead.
   void AddItem(std::unique_ptr<AppListItem> app_item);
@@ -110,9 +118,12 @@ class AppListSyncableService : public syncer::SyncableService,
   void SetPinPosition(const std::string& app_id,
                       const syncer::StringOrdinal& item_pin_ordinal);
 
-  // Gets the app list model, building it if it doesn't yet exist.
+  // Gets the app list model.
   AppListModel* GetModel();
 
+  // Returns true if this service was initialized.
+  bool IsInitialized() const;
+
   // Registers new observers and makes sure that service is started.
   void AddObserverAndStart(Observer* observer);
   void RemoveObserver(Observer* observer);
@@ -229,9 +240,20 @@ class AppListSyncableService : public syncer::SyncableService,
   // an OEM (extension->was_installed_by_oem() is true).
   bool AppIsOem(const std::string& id);
 
+  // Initializes sync items from the local storage while sync service is not
+  // enabled.
+  void InitFromLocalStorage();
+
   // Helper that notifies observers that sync model has been updated.
   void NotifyObserversSyncUpdated();
 
+  // Handles model update start/finish.
+  void HandleUpdateStarted();
+  void HandleUpdateFinished();
+
+  // Returns true if extension service is ready.
+  bool IsExtensionServiceReady() const;
+
   Profile* profile_;
   extensions::ExtensionSystem* extension_system_;
   std::unique_ptr<AppListModel> model_;
@@ -254,6 +276,8 @@ class AppListSyncableService : public syncer::SyncableService,
   // Provides integration with Drive apps.
   std::unique_ptr<DriveAppProvider> drive_app_provider_;
 
+  base::WeakPtrFactory<AppListSyncableService> weak_ptr_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(AppListSyncableService);
 };