Gtk3 ui: Add libgtk3ui as a separate build component

chrome/browser/ui/libgtk2ui/chrome_gtk_frame.h

-// 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 CHROME_BROWSER_UI_LIBGTK2UI_CHROME_GTK_FRAME_H_
-#define CHROME_BROWSER_UI_LIBGTK2UI_CHROME_GTK_FRAME_H_
-
-#include <gtk/gtk.h>
-
-G_BEGIN_DECLS
-
-// This file declares two subclasses of GtkWindow for easier gtk+ theme
-// integration.
-//
-// The first is "MetaFrames," which is (was?) the name of a gobject class in
-// the metacity window manager. To actually get at those values, we need to
-// have an object whose gobject class name string matches the definitions in
-// the gtkrc file. MetaFrames derives from GtkWindow.
-//
-// Metaframes can not be instantiated. It has no constructor; instantiate
-// ChromeGtkFrame instead.
-typedef struct _MetaFrames       MetaFrames;
-typedef struct _MetaFramesClass  MetaFramesClass;
-
-struct _MetaFrames {
-  GtkWindow window;
-};
-
-struct _MetaFramesClass {
-  GtkWindowClass parent_class;
-};
-
-
-// The second is ChromeGtkFrame, which defines a number of optional style
-// properties so theme authors can control how chromium appears in gtk-theme
-// mode.  It derives from MetaFrames in chrome so older themes that declare a
-// MetaFrames theme will still work. New themes should target this class.
-typedef struct _ChromeGtkFrame       ChromeGtkFrame;
-typedef struct _ChromeGtkFrameClass  ChromeGtkFrameClass;
-
-struct _ChromeGtkFrame {
-  MetaFrames frames;
-};
-
-struct _ChromeGtkFrameClass {
-  MetaFramesClass frames_class;
-};
-
-// Creates a GtkWindow object the the class name "ChromeGtkFrame".
-GtkWidget* chrome_gtk_frame_new();
-
-G_END_DECLS
-
-#endif  // CHROME_BROWSER_UI_LIBGTK2UI_CHROME_GTK_FRAME_H_