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

chrome/browser/extensions/api/storage/settings_frontend.cc

 // Copyright (c) 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.
 
 #include "chrome/browser/extensions/api/storage/settings_frontend.h"
 
 #include <limits>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/files/file_path.h"
 #include "base/json/json_reader.h"
 #include "chrome/browser/extensions/api/storage/leveldb_settings_storage_factory.h"
-#include "chrome/browser/extensions/api/storage/settings_backend.h"
 #include "chrome/browser/extensions/api/storage/sync_or_local_value_store_cache.h"
 #include "chrome/browser/extensions/event_names.h"
 #include "chrome/browser/extensions/extension_service.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/common/extensions/api/storage.h"
 #include "content/public/browser/browser_thread.h"
 #include "extensions/browser/event_router.h"
 #include "extensions/browser/extension_system.h"
 
 #if defined(ENABLE_CONFIGURATION_POLICY)
@@ skipping 114 matching lines @@
   }
 }
 
 syncer::SyncableService* SettingsFrontend::GetBackendForSync(
     syncer::ModelType type) const {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
   CacheMap::const_iterator it = caches_.find(settings_namespace::SYNC);
   DCHECK(it != caches_.end());
   const SyncOrLocalValueStoreCache* sync_cache =
       static_cast<const SyncOrLocalValueStoreCache*>(it->second);
-  switch (type) {
-    case syncer::APP_SETTINGS:
-      return sync_cache->GetAppBackend();
-    case syncer::EXTENSION_SETTINGS:
-      return sync_cache->GetExtensionBackend();
-    default:
-      NOTREACHED();
-      return NULL;
-  }
+  DCHECK(type == syncer::APP_SETTINGS || type == syncer::EXTENSION_SETTINGS);
+  return sync_cache->GetSyncableService(type);
 }
 
 bool SettingsFrontend::IsStorageEnabled(
     settings_namespace::Namespace settings_namespace) const {
   return caches_.find(settings_namespace) != caches_.end();
 }
 
 void SettingsFrontend::RunWithStorage(
     const std::string& extension_id,
     settings_namespace::Namespace settings_namespace,
@@ skipping 41 matching lines @@
   CacheMap::iterator it = caches_.find(settings_namespace);
   if (it != caches_.end()) {
     ValueStoreCache* cache = it->second;
     cache->ShutdownOnUI();
     BrowserThread::DeleteSoon(BrowserThread::FILE, FROM_HERE, cache);
     caches_.erase(it);
   }
 }
 
 }  // namespace extensions