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

ash/shell_context_menu.h

Index: ash/shell_context_menu.h
diff --git a/ash/shell_context_menu.h b/ash/shell_context_menu.h
new file mode 100644
index 0000000000000000000000000000000000000000..555e1d5193d709b0606afb44d418b9b67b5d8206
--- /dev/null
+++ b/ash/shell_context_menu.h
@@ -0,0 +1,54 @@
+// 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 ASH_SHELL_CONTEXT_MENU_H_
+#define ASH_SHELL_CONTEXT_MENU_H_
+#pragma once
+
+#include "base/memory/scoped_ptr.h"
+#include "ui/base/models/simple_menu_model.h"
+
+namespace gfx {
+class Point;
+class Size;
+}
+
+namespace views {
+class MenuRunner;
+class Widget;
+}
+
+namespace ash {
+namespace internal {
+
+class ShellContextMenu : public ui::SimpleMenuModel::Delegate {
+ public:
+  ShellContextMenu();
+  virtual ~ShellContextMenu();
+
+  // Shows the context menu when right click on background.
+  void ShowMenu(views::Widget* widget, const gfx::Point& location);
+
+  // ui::SimpleMenuModel::Delegate overrides:
+  virtual bool IsCommandIdChecked(int command_id) const OVERRIDE;
+  virtual bool IsCommandIdEnabled(int command_id) const OVERRIDE;
+  virtual void ExecuteCommand(int command_id) OVERRIDE;
+  virtual bool GetAcceleratorForCommandId(
+      int command_id,
+      ui::Accelerator* accelerator) OVERRIDE;
+
+ private:
+  enum MenuItem {
+    MENU_CHANGE_WALLPAPER,
+  };
+
+  scoped_ptr<views::MenuRunner> menu_runner_;
+
+  DISALLOW_COPY_AND_ASSIGN(ShellContextMenu);
+};
+
+}  // namespace internal
+}  // namespace ash
+
+#endif  // ASH_SHELL_CONTEXT_MENU_H_