gtk: Use gtk_dialog_get_content_area() throughout.

chrome/browser/ui/gtk/about_chrome_dialog.cc

 // Copyright (c) 2011 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 "chrome/browser/ui/gtk/about_chrome_dialog.h"
 
 #include <gtk/gtk.h>
 
 #include <string>
 #include <vector>
@@ skipping 100 matching lines @@
       NULL);
   // Pick up the style set in gtk_util.cc:InitRCStyles().
   // The layout of this dialog is special because the logo should be flush
   // with the edges of the window.
   gtk_widget_set_name(dialog, "about-dialog");
   gtk_dialog_set_has_separator(GTK_DIALOG(dialog), FALSE);
 
   GtkWidget* close_button = gtk_dialog_add_button(GTK_DIALOG(dialog),
       GTK_STOCK_CLOSE, GTK_RESPONSE_CLOSE);
 
-  GtkWidget* content_area = GTK_DIALOG(dialog)->vbox;
+  GtkWidget* content_area = gtk_dialog_get_content_area(GTK_DIALOG(dialog));
 
   // Use an event box to get the background painting correctly
   GtkWidget* ebox = gtk_event_box_new();
   gtk_widget_set_app_paintable(ebox, TRUE);
   g_signal_connect(ebox, "expose-event", G_CALLBACK(OnEventBoxExpose), NULL);
 
   GtkWidget* hbox = gtk_hbox_new(FALSE, 0);
 
   GtkWidget* text_alignment = gtk_alignment_new(0.0, 0.0, 1.0, 1.0);
   gtk_alignment_set_padding(GTK_ALIGNMENT(text_alignment),
@@ skipping 138 matching lines @@
       gtk_util::kContentAreaBorder, 0,
       gtk_util::kContentAreaBorder, gtk_util::kContentAreaBorder);
   gtk_container_add(GTK_CONTAINER(alignment), vbox);
   gtk_box_pack_start(GTK_BOX(content_area), alignment, FALSE, FALSE, 0);
 
   g_signal_connect(dialog, "response", G_CALLBACK(OnResponse), NULL);
   gtk_window_set_resizable(GTK_WINDOW(dialog), FALSE);
   gtk_widget_show_all(dialog);
   gtk_widget_grab_focus(close_button);
 }