Move Extension into extensions namespace

chrome/browser/extensions/convert_web_app.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_CONVERT_WEB_APP_H_
 #define CHROME_BROWSER_EXTENSIONS_CONVERT_WEB_APP_H_
 #pragma once
 
 #include <string>
 
 #include "base/memory/ref_counted.h"
 
-class Extension;
 
 namespace base {
 class Time;
 }
 
+namespace extensions {
+class Extension;
+}
+
 struct WebApplicationInfo;
 
 // Generates a version number for an extension from a time. The goal is to make
 // use of the version number to communicate the date in a human readable form,
 // while maintaining high enough resolution to change each time an app is
 // reinstalled. The version that is returned has the format:
 //
 // <year>.<month>.<day>.<fraction>
 //
 // fraction is represented as a number between 0 and 2^16-1. Each unit is
 // ~1.32 seconds.
 std::string ConvertTimeToExtensionVersion(const base::Time& time);
 
 // Wraps the specified web app in an extension. The extension is created
 // unpacked in the system temp dir. Returns a valid extension that the caller
 // should take ownership on success, or NULL and |error| on failure.
 //
 // NOTE: This function does file IO and should not be called on the UI thread.
 // NOTE: The caller takes ownership of the directory at extension->path() on the
 // returned object.
-scoped_refptr<Extension> ConvertWebAppToExtension(
+scoped_refptr<extensions::Extension> ConvertWebAppToExtension(
     const WebApplicationInfo& web_app_info,
     const base::Time& create_time);
 
 #endif  // CHROME_BROWSER_EXTENSIONS_CONVERT_WEB_APP_H_