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

chrome/browser/extensions/api/storage/leveldb_settings_storage_factory.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/leveldb_settings_storage_factory.h"
 
+#include "base/file_util.h"
 #include "base/logging.h"
 #include "chrome/browser/value_store/leveldb_value_store.h"
 
 namespace extensions {
 
+namespace {
+
+base::FilePath GetDatabasePath(const base::FilePath& base_path,
+                               const std::string& extension_id) {
+  return base_path.AppendASCII(extension_id);
+}
+
+}  // namespace
+
 ValueStore* LeveldbSettingsStorageFactory::Create(
     const base::FilePath& base_path,
     const std::string& extension_id) {
-  return new LeveldbValueStore(base_path.AppendASCII(extension_id));
+  return new LeveldbValueStore(GetDatabasePath(base_path, extension_id));
+}
+
+void LeveldbSettingsStorageFactory::DeleteDatabaseIfExists(
+    const base::FilePath& base_path,
+    const std::string& extension_id) {
+  base::FilePath path = GetDatabasePath(base_path, extension_id);
+  if (base::PathExists(path))
+    base::DeleteFile(path, true /* recursive */);
 }
 
 }  // namespace extensions