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

ash/shell_context_menu.cc

Index: ash/shell_context_menu.cc
diff --git a/ash/shell_context_menu.cc b/ash/shell_context_menu.cc
new file mode 100644
index 0000000000000000000000000000000000000000..a874f50afc0bb5da28af97a68af6b2748964d700
--- /dev/null
+++ b/ash/shell_context_menu.cc
@@ -0,0 +1,64 @@
+// 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 "ash/shell_context_menu.h"
+
+#include "ash/desktop_background/desktop_background_controller.h"
+#include "ash/shell.h"
+#include "grit/ash_strings.h"
+#include "ui/base/l10n/l10n_util.h"
+#include "ui/views/controls/menu/menu_model_adapter.h"
+#include "ui/views/controls/menu/menu_runner.h"
+
+namespace ash {
+namespace internal {
+
+ShellContextMenu::ShellContextMenu() {
+}
+
+ShellContextMenu::~ShellContextMenu() {
+}
+
+void ShellContextMenu::ShowMenu(views::Widget* widget,
+                                const gfx::Point& location) {
+  if (Shell::GetInstance()->user_wallpaper_delegate()->IsLoggedInAsGuest())
+    return;
+  ui::SimpleMenuModel menu_model(this);
+  menu_model.AddItem(MENU_CHANGE_WALLPAPER,
+      l10n_util::GetStringUTF16(IDS_AURA_SET_DESKTOP_WALLPAPER));
+  views::MenuModelAdapter menu_model_adapter(&menu_model);
+  menu_runner_.reset(new views::MenuRunner(menu_model_adapter.CreateMenu()));
+  if (menu_runner_->RunMenuAt(
+          widget, NULL, gfx::Rect(location, gfx::Size()),
+          views::MenuItemView::TOPRIGHT, views::MenuRunner::HAS_MNEMONICS) ==
+      views::MenuRunner::MENU_DELETED)
+    return;
+}
+
+bool ShellContextMenu::IsCommandIdChecked(int command_id) const {
+  return false;
+}
+
+bool ShellContextMenu::IsCommandIdEnabled(int command_id) const {
+  return true;
+}
+
+void ShellContextMenu::ExecuteCommand(int command_id) {
+  switch (static_cast<MenuItem>(command_id)) {
+    case MENU_CHANGE_WALLPAPER: {
+      Shell::GetInstance()->user_wallpaper_delegate()->
+          OpenSetWallpaperPage();
+      break;
+    }
+  }
+}
+
+bool ShellContextMenu::GetAcceleratorForCommandId(
+      int command_id,
+      ui::Accelerator* accelerator) {
+  return false;
+}
+
+}  // namespace internal
+}  // namespace ash