Remove "set wallpaper..." option in system context menu when guest logged in

chrome/browser/chromeos/background/desktop_background_observer.cc

 // 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.
 
 #include "chrome/browser/chromeos/background/desktop_background_observer.h"
 
 #include "ash/shell.h"
 #include "ash/desktop_background/desktop_background_controller.h"
 #include "ash/desktop_background/desktop_background_resources.h"
 #include "base/logging.h"
@@ skipping 19 matching lines @@
   virtual const int GetUserWallpaperIndex() OVERRIDE {
     return chromeos::UserManager::Get()->GetUserWallpaperIndex();
   }
 
   virtual void OpenSetWallpaperPage() OVERRIDE {
     Browser* browser = Browser::GetOrCreateTabbedBrowser(
         ProfileManager::GetDefaultProfileOrOffTheRecord());
     browser->ShowOptionsTab("setWallpaper");
   }
 
+  virtual bool IsLoggedInAsGuest() OVERRIDE {
+    return chromeos::UserManager::Get()->IsLoggedInAsGuest();
+  }
+
  private:
   DISALLOW_COPY_AND_ASSIGN(UserWallpaperDelegate);
 };
 
 }  // namespace
 
 ash::UserWallpaperDelegate* CreateUserWallpaperDelegate() {
   return new chromeos::UserWallpaperDelegate();
 }
 
@@ skipping 15 matching lines @@
       ash::Shell::GetInstance()->desktop_background_controller()->
           OnDesktopBackgroundChanged();
       break;
     }
     default:
       NOTREACHED();
   }
 }
 
 }  // namespace chromeos