GTK: Seal up GSEALs, focusing on GtkSelectionData.

ui/base/x/x11_util.cc

 // 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.
 
 // This file defines utility functions for X11 (Linux only). This code has been
 // ported from XCB since we can't use XCB on Ubuntu while its 32-bit support
 // remains woefully incomplete.
 
 #include "ui/base/x/x11_util.h"
 
@@ skipping 307 matching lines @@
 XID GetX11RootWindow() {
   return DefaultRootWindow(GetXDisplay());
 }
 
 bool GetCurrentDesktop(int* desktop) {
   return GetIntProperty(GetX11RootWindow(), "_NET_CURRENT_DESKTOP", desktop);
 }
 
 #if defined(TOOLKIT_USES_GTK)
 XID GetX11WindowFromGtkWidget(GtkWidget* widget) {
-  return GDK_WINDOW_XID(widget->window);
+  return GDK_WINDOW_XID(gtk_widget_get_window(widget));
 }
 
 XID GetX11WindowFromGdkWindow(GdkWindow* window) {
   return GDK_WINDOW_XID(window);
 }
 
 GtkWindow* GetGtkWindowFromX11Window(XID xid) {
   GdkWindow* gdk_window =
       gdk_x11_window_lookup_for_display(gdk_display_get_default(), xid);
   if (!gdk_window)
@@ skipping 750 matching lines @@
       << "request_code " << static_cast<int>(error_event.request_code) << ", "
       << "minor_code " << static_cast<int>(error_event.minor_code)
       << " (" << request_str << ")";
 }
 
 // ----------------------------------------------------------------------------
 // End of x11_util_internal.h
 
 
 }  // namespace ui