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

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

Index: chrome/browser/extensions/api/storage/sync_storage_backend.h
diff --git a/chrome/browser/extensions/api/storage/settings_backend.h b/chrome/browser/extensions/api/storage/sync_storage_backend.h
similarity index 72%
copy from chrome/browser/extensions/api/storage/settings_backend.h
copy to chrome/browser/extensions/api/storage/sync_storage_backend.h
index 0882b68ed3538996b8767075c802c5813026b9c3..ab84b71b27c9585f5e012c82677fad8bff348182 100644
--- a/chrome/browser/extensions/api/storage/settings_backend.h
+++ b/chrome/browser/extensions/api/storage/sync_storage_backend.h
@@ -1,9 +1,9 @@
-// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// 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_SETTINGS_BACKEND_H_
-#define CHROME_BROWSER_EXTENSIONS_API_STORAGE_SETTINGS_BACKEND_H_
+#ifndef CHROME_BROWSER_EXTENSIONS_API_STORAGE_SYNC_STORAGE_BACKEND_H_
+#define CHROME_BROWSER_EXTENSIONS_API_STORAGE_SYNC_STORAGE_BACKEND_H_
 
 #include <map>
 #include <set>
@@ -14,6 +14,7 @@
 #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"
@@ -31,32 +32,31 @@ class SyncableSettingsStorage;
 // Manages ValueStore objects for extensions, including routing
 // changes from sync to them.
 // Lives entirely on the FILE thread.
-class SettingsBackend : public syncer::SyncableService {
+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.
-  SettingsBackend(
+  SyncStorageBackend(
       const scoped_refptr<SettingsStorageFactory>& storage_factory,
       const base::FilePath& base_path,
-      syncer::ModelType sync_type,
-      const syncer::SyncableService::StartSyncFlare& flare,
       const SettingsStorageQuotaEnforcer::Limits& quota,
-      const scoped_refptr<SettingsObserverList>& observers);
-
-  virtual ~SettingsBackend();
+      const scoped_refptr<SettingsObserverList>& observers,
+      syncer::ModelType sync_type,
+      const syncer::SyncableService::StartSyncFlare& flare);
 
-  // Gets a weak reference to the storage area for |extension_id|.
-  // Must be run on the FILE thread.
-  ValueStore* GetStorage(const std::string& extension_id) const;
+  virtual ~SyncStorageBackend();
 
-  // Deletes all setting data for an extension. Call on the FILE thread.
-  void DeleteStorage(const std::string& extension_id);
+  // 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::SyncDataList GetAllSyncData(syncer::ModelType type)
+      const OVERRIDE;
   virtual syncer::SyncMergeResult MergeDataAndStartSyncing(
       syncer::ModelType type,
       const syncer::SyncDataList& initial_sync_data,
@@ -82,15 +82,6 @@ class SettingsBackend : public syncer::SyncableService {
   scoped_ptr<SettingsSyncProcessor> CreateSettingsSyncProcessor(
       const std::string& extension_id) const;
 
-  // The Factory to use for creating leveldb storage areas.
-  const scoped_refptr<SettingsStorageFactory> storage_factory_;
-
-  // The base file path to create any leveldb databases at.
-  const base::FilePath base_path_;
-
-  // Quota limits (see SettingsStorageQuotaEnforcer).
-  const SettingsStorageQuotaEnforcer::Limits quota_;
-
   // The list of observers to settings changes.
   const scoped_refptr<SettingsObserverList> observers_;
 
@@ -111,9 +102,9 @@ class SettingsBackend : public syncer::SyncableService {
 
   syncer::SyncableService::StartSyncFlare flare_;
 
-  DISALLOW_COPY_AND_ASSIGN(SettingsBackend);
+  DISALLOW_COPY_AND_ASSIGN(SyncStorageBackend);
 };
 
 }  // namespace extensions
 
-#endif  // CHROME_BROWSER_EXTENSIONS_API_STORAGE_SETTINGS_BACKEND_H_
+#endif  // CHROME_BROWSER_EXTENSIONS_API_STORAGE_SYNC_STORAGE_BACKEND_H_