Gtk3 ui: Add libgtk3ui as a separate build component

chrome/browser/ui/libgtkui/menu_util.h

 // Copyright 2013 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_LIBGTK2UI_MENU_UTIL_H_
-#define CHROME_BROWSER_UI_LIBGTK2UI_MENU_UTIL_H_
+#ifndef CHROME_BROWSER_UI_LIBGTKUI_MENU_UTIL_H_
+#define CHROME_BROWSER_UI_LIBGTKUI_MENU_UTIL_H_
 
 #include <gtk/gtk.h>
 
 #include "ui/gfx/image/image.h"
 
 namespace ui {
 class MenuModel;
 }
 
-namespace libgtk2ui {
+namespace libgtkui {
 // Builds GtkImageMenuItems.
 GtkWidget* BuildMenuItemWithImage(const std::string& label, GtkWidget* image);
 GtkWidget* BuildMenuItemWithImage(const std::string& label,
                                   const gfx::Image& icon);
 GtkWidget* BuildMenuItemWithLabel(const std::string& label);
 
 ui::MenuModel* ModelForMenuItem(GtkMenuItem* menu_item);
 
 // This method is used to build the menu dynamically. The return value is the
 // new menu item.
@@ skipping 17 matching lines @@
 // See comments in definition of SetMenuItemInfo for more info.
 void BuildSubmenuFromModel(ui::MenuModel* model,
                            GtkWidget* menu,
                            GCallback item_activated_cb,
                            bool* block_activation,
                            void* this_ptr);
 
 // Sets the check mark, enabled/disabled state and dynamic labels on menu items.
 void SetMenuItemInfo(GtkWidget* widget, void* block_activation_ptr);
 
-}  // namespace libgtk2ui
+}  // namespace libgtkui
 
-#endif  // CHROME_BROWSER_UI_LIBGTK2UI_MENU_UTIL_H_
+#endif  // CHROME_BROWSER_UI_LIBGTKUI_MENU_UTIL_H_