Implement an initial extension settings API.

chrome/browser/extensions/extension_settings_leveldb_storage.h

+// Copyright (c) 2011 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_EXTENSION_SETTINGS_LEVELDB_STORAGE_H_
+#define CHROME_BROWSER_EXTENSIONS_EXTENSION_SETTINGS_LEVELDB_STORAGE_H_
+#pragma once
+
+#include "base/compiler_specific.h"
+#include "base/file_path.h"
+#include "base/scoped_ptr.h"
+#include "chrome/browser/extensions/extension_settings_storage.h"
+#include "third_party/leveldb/include/leveldb/db.h"
+
+// Extension settings storage object, backed by a leveldb database.
+// No caching is done; that should be handled by wrapping with an
+// ExtensionSettingsStorageCache.
+class ExtensionSettingsLeveldbStorage : public ExtensionSettingsStorage {
+ public:
+  // Tries to create a leveldb storage area for an extension at a base path.
+  // Returns NULL if creation fails.
+  // Must be run on the FILE thread.
+  static ExtensionSettingsLeveldbStorage* Create(
+      const FilePath& base_path, const std::string& extension_id);
+
+  // Can be run on any thread.
+  virtual void DestroyEventually() OVERRIDE;
+
+  virtual void Get(const std::string& key, Callback* callback) OVERRIDE;
+  virtual void Get(const ListValue& keys, Callback* callback) OVERRIDE;
+  virtual void Get(Callback* callback) OVERRIDE;
+  virtual void Set(
+      const std::string& key, const Value& value, Callback* callback) OVERRIDE;
+  virtual void Set(const DictionaryValue& values, Callback* callback) OVERRIDE;
+  virtual void Remove(const std::string& key, Callback* callback) OVERRIDE;
+  virtual void Remove(const ListValue& keys, Callback* callback) OVERRIDE;
+  virtual void Clear(Callback *callback) OVERRIDE;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(ExtensionSettingsLeveldbStorage);
+
+  // Ownership of db is taken.
+  explicit ExtensionSettingsLeveldbStorage(leveldb::DB* db);
+  // Must be destructed on the FILE thread.
+  ~ExtensionSettingsLeveldbStorage();
+
+  scoped_ptr<leveldb::DB> db_;
+};
+
+#endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_SETTINGS_LEVELDB_STORAGE_H_