Revert of Add a Restore() method to ValueStore and make StorageAPI use it

chrome/browser/extensions/api/storage/sync_storage_backend.h

-// Copyright 2014 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_EXTENSIONS_API_STORAGE_SYNC_STORAGE_BACKEND_H_
-#define CHROME_BROWSER_EXTENSIONS_API_STORAGE_SYNC_STORAGE_BACKEND_H_
-
-#include <map>
-#include <set>
-#include <string>
-
-#include "base/compiler_specific.h"
-#include "base/files/file_path.h"
-#include "base/memory/linked_ptr.h"
-#include "base/memory/ref_counted.h"
-#include "base/memory/scoped_ptr.h"
-#include "chrome/browser/extensions/api/storage/settings_backend.h"
-#include "chrome/browser/extensions/api/storage/settings_observer.h"
-#include "chrome/browser/extensions/api/storage/settings_storage_factory.h"
-#include "chrome/browser/extensions/api/storage/settings_storage_quota_enforcer.h"
-#include "sync/api/syncable_service.h"
-
-namespace syncer {
-class SyncErrorFactory;
-}
-
-namespace extensions {
-
-class SettingsSyncProcessor;
-class SyncableSettingsStorage;
-
-// Manages ValueStore objects for extensions, including routing
-// changes from sync to them.
-// Lives entirely on the FILE thread.
-class SyncStorageBackend : public SettingsBackend,
-                           public syncer::SyncableService {
- public:
-  // |storage_factory| is use to create leveldb storage areas.
-  // |base_path| is the base of the extension settings directory, so the
-  // databases will be at base_path/extension_id.
-  // |observers| is the list of observers to settings changes.
-  SyncStorageBackend(
-      const scoped_refptr<SettingsStorageFactory>& storage_factory,
-      const base::FilePath& base_path,
-      const SettingsStorageQuotaEnforcer::Limits& quota,
-      const scoped_refptr<SettingsObserverList>& observers,
-      syncer::ModelType sync_type,
-      const syncer::SyncableService::StartSyncFlare& flare);
-
-  virtual ~SyncStorageBackend();
-
-  // SettingsBackend implementation.
-  virtual ValueStore* GetStorage(const std::string& extension_id) OVERRIDE;
-  virtual void DeleteStorage(const std::string& extension_id) OVERRIDE;
-  virtual syncer::SyncableService* GetAsSyncableService() OVERRIDE;
-
-  // syncer::SyncableService implementation.
-  virtual syncer::SyncDataList GetAllSyncData(syncer::ModelType type)
-      const OVERRIDE;
-  virtual syncer::SyncMergeResult MergeDataAndStartSyncing(
-      syncer::ModelType type,
-      const syncer::SyncDataList& initial_sync_data,
-      scoped_ptr<syncer::SyncChangeProcessor> sync_processor,
-      scoped_ptr<syncer::SyncErrorFactory> sync_error_factory) OVERRIDE;
-  virtual syncer::SyncError ProcessSyncChanges(
-      const tracked_objects::Location& from_here,
-      const syncer::SyncChangeList& change_list) OVERRIDE;
-  virtual void StopSyncing(syncer::ModelType type) OVERRIDE;
-
- private:
-  // Gets a weak reference to the storage area for a given extension,
-  // initializing sync with some initial data if sync enabled.
-  SyncableSettingsStorage* GetOrCreateStorageWithSyncData(
-      const std::string& extension_id,
-      const base::DictionaryValue& sync_data) const;
-
-  // Gets all extension IDs known to extension settings.  This may not be all
-  // installed extensions.
-  std::set<std::string> GetKnownExtensionIDs() const;
-
-  // Creates a new SettingsSyncProcessor for an extension.
-  scoped_ptr<SettingsSyncProcessor> CreateSettingsSyncProcessor(
-      const std::string& extension_id) const;
-
-  // The list of observers to settings changes.
-  const scoped_refptr<SettingsObserverList> observers_;
-
-  // A cache of ValueStore objects that have already been created.
-  // Ensure that there is only ever one created per extension.
-  typedef std::map<std::string, linked_ptr<SyncableSettingsStorage> >
-      StorageObjMap;
-  mutable StorageObjMap storage_objs_;
-
-  // Current sync model type. Either EXTENSION_SETTINGS or APP_SETTINGS.
-  syncer::ModelType sync_type_;
-
-  // Current sync processor, if any.
-  scoped_ptr<syncer::SyncChangeProcessor> sync_processor_;
-
-  // Current sync error handler if any.
-  scoped_ptr<syncer::SyncErrorFactory> sync_error_factory_;
-
-  syncer::SyncableService::StartSyncFlare flare_;
-
-  DISALLOW_COPY_AND_ASSIGN(SyncStorageBackend);
-};
-
-}  // namespace extensions
-
-#endif  // CHROME_BROWSER_EXTENSIONS_API_STORAGE_SYNC_STORAGE_BACKEND_H_