Move small c/b/extensions classes into extensions namespace no.1

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