Gtk3 ui: Add libgtk3ui as a separate build component

chrome/browser/ui/libgtk2ui/chrome_gtk_menu_subclasses.h

Index: chrome/browser/ui/libgtk2ui/chrome_gtk_menu_subclasses.h
diff --git a/chrome/browser/ui/libgtk2ui/chrome_gtk_menu_subclasses.h b/chrome/browser/ui/libgtk2ui/chrome_gtk_menu_subclasses.h
deleted file mode 100644
index 6cc31ca0d60d396faa51026a18d099b40a4de8ab..0000000000000000000000000000000000000000
--- a/chrome/browser/ui/libgtk2ui/chrome_gtk_menu_subclasses.h
+++ /dev/null
@@ -1,47 +0,0 @@
-// 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_CHROME_GTK_MENU_SUBCLASSES_H_
-#define CHROME_BROWSER_UI_LIBGTK2UI_CHROME_GTK_MENU_SUBCLASSES_H_
-
-#include <gtk/gtk.h>
-
-// This file declares two subclasses of Gtk's menu classes. We do this because
-// when we were a GTK app proper, we had classes with the same names, and gtk
-// theme authors started writing themes and styling chrome's menus by targeting
-// these classes. We have to fetch our colors from these theme classes in
-// specific because several newer GTK+2 themes are pixmap based and they
-// specifically give real colors only to these classes.
-
-G_BEGIN_DECLS
-
-typedef struct _GtkCustomMenu GtkCustomMenu;
-typedef struct _GtkCustomMenuClass GtkCustomMenuClass;
-
-struct _GtkCustomMenu {
-  GtkMenu menu;
-};
-
-struct _GtkCustomMenuClass {
-  GtkMenuClass parent_class;
-};
-
-GtkWidget* gtk_custom_menu_new();
-
-typedef struct _GtkCustomMenuItem GtkCustomMenuItem;
-typedef struct _GtkCustomMenuItemClass GtkCustomMenuItemClass;
-
-struct _GtkCustomMenuItem {
-  GtkMenuItem menu_item;
-};
-
-struct _GtkCustomMenuItemClass {
-  GtkMenuItemClass parent_class;
-};
-
-GtkWidget* gtk_custom_menu_item_new();
-
-G_END_DECLS
-
-#endif  // CHROME_BROWSER_UI_LIBGTK2UI_CHROME_GTK_MENU_SUBCLASSES_H_