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

chrome/browser/value_store/leveldb_value_store.h

 // 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.
 
 #ifndef CHROME_BROWSER_VALUE_STORE_LEVELDB_VALUE_STORE_H_
 #define CHROME_BROWSER_VALUE_STORE_LEVELDB_VALUE_STORE_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 27 matching lines @@
   virtual ReadResult Get() OVERRIDE;
   virtual WriteResult Set(
       WriteOptions options,
       const std::string& key,
       const base::Value& value) OVERRIDE;
   virtual WriteResult Set(
       WriteOptions options, const base::DictionaryValue& values) OVERRIDE;
   virtual WriteResult Remove(const std::string& key) OVERRIDE;
   virtual WriteResult Remove(const std::vector<std::string>& keys) OVERRIDE;
   virtual WriteResult Clear() OVERRIDE;
+  virtual bool Restore() OVERRIDE;
+  virtual bool RestoreKey(const std::string& key) OVERRIDE;
+
+  // Write directly to the backing levelDB. Only used for testing to cause
+  // corruption in the database.
+  bool WriteToDbForTest(leveldb::WriteBatch* batch);
 
  private:
   // Tries to open the database if it hasn't been opened already.
   scoped_ptr<ValueStore::Error> EnsureDbIsOpen();
 
   // Reads a setting from the database.
   scoped_ptr<ValueStore::Error> ReadFromDb(
       leveldb::ReadOptions options,
       const std::string& key,
       // Will be reset() with the result, if any.
@@ skipping 26 matching lines @@
   // The location of the leveldb backend.
   const base::FilePath db_path_;
 
   // leveldb backend.
   scoped_ptr<leveldb::DB> db_;
 
   DISALLOW_COPY_AND_ASSIGN(LeveldbValueStore);
 };
 
 #endif  // CHROME_BROWSER_VALUE_STORE_LEVELDB_VALUE_STORE_H_