Move Extension into extensions namespace

chrome/browser/ui/webui/extensions/extension_activity_ui.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_UI_WEBUI_EXTENSIONS_EXTENSION_ACTIVITY_UI_H_
 #define CHROME_BROWSER_UI_WEBUI_EXTENSIONS_EXTENSION_ACTIVITY_UI_H_
 #pragma once
 
 #include "chrome/browser/extensions/extension_activity_log.h"
 #include "content/public/browser/web_ui_controller.h"
 
+namespace extensions {
+class Extension;
+}
+
 class ExtensionActivityUI : public content::WebUIController,
                             public ExtensionActivityLog::Observer {
  public:
   explicit ExtensionActivityUI(content::WebUI* web_ui);
   virtual ~ExtensionActivityUI();
 
   // Callback for "requestExtensionData".
   void HandleRequestExtensionData(const base::ListValue* args);
 
   // ExtensionActivityLog::Observer implementation.
-  virtual void OnExtensionActivity(const Extension* extension,
+  virtual void OnExtensionActivity(const extensions::Extension* extension,
                                    ExtensionActivityLog::Activity activity,
                                    const std::string& msg) OVERRIDE;
 
  private:
-  const Extension* extension_;
+  const extensions::Extension* extension_;
 
   DISALLOW_COPY_AND_ASSIGN(ExtensionActivityUI);
 };
 
 #endif  // CHROME_BROWSER_UI_WEBUI_EXTENSIONS_EXTENSION_ACTIVITY_UI_H_