Implement an initial extension settings API.

chrome/browser/extensions/extension_settings_leveldb_storage.h

Index: chrome/browser/extensions/extension_settings_leveldb_storage.h
diff --git a/chrome/browser/extensions/extension_settings_leveldb_storage.h b/chrome/browser/extensions/extension_settings_leveldb_storage.h
new file mode 100644
index 0000000000000000000000000000000000000000..699b8b46b318935a72b46e2b8c5b511400d01884
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+++ b/chrome/browser/extensions/extension_settings_leveldb_storage.h
@@ -0,0 +1,59 @@
+// 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/memory/ref_counted.h"
+#include "base/scoped_ptr.h"
+#include "base/task.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 DeleteSoon() 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:
+  // Ownership of db is taken.
+  explicit ExtensionSettingsLeveldbStorage(leveldb::DB* db);
+
+  // This must only be deleted on the FILE thread.
+  friend class DeleteTask<ExtensionSettingsLeveldbStorage>;
+  virtual ~ExtensionSettingsLeveldbStorage();
+
+  // leveldb backend.
+  scoped_ptr<leveldb::DB> db_;
+
+  // Whether this has or is about to be deleted on the FILE thread.
+  // Used to prevent any use of this after DeleteSoon() is called.
+  bool marked_for_deletion_;
+
+  DISALLOW_COPY_AND_ASSIGN(ExtensionSettingsLeveldbStorage);
+};
+
+#endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_SETTINGS_LEVELDB_STORAGE_H_