Extension Settings API: move the API functions into an object SettingsNamepace,

chrome/browser/extensions/settings/settings_namespace.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_SETTINGS_SETTINGS_NAMESPACE_H_
+#define CHROME_BROWSER_EXTENSIONS_SETTINGS_SETTINGS_NAMESPACE_H_
+#pragma once
+
+#include <string>
+
+namespace extensions {
+
+namespace settings_namespace {
+
+// The namespaces of the storage areas.
+enum Namespace {
+  LOCAL,  // "local" i.e. chrome.experimental.settings.local
+  SYNC,   // "sync"  i.e. chrome.experimental.settings.sync
+  INVALID
+};
+
+// Converts a namespace to its string representation.
+// Namespace must not be INVALID.
+std::string ToString(Namespace settings_namespace);
+
+// Converts a string representation of a namespace to its namespace, or INVALID
+// if the string doesn't map to one.
+Namespace FromString(const std::string& ns_string);
+
+}  // namespace settings_namespace
+
+}  // namespace extensions
+
+#endif  // CHROME_BROWSER_EXTENSIONS_SETTINGS_SETTINGS_NAMESPACE_H_