GTK: More raw struct access removal, this time focusing on GtkDialog.

chrome/browser/ui/gtk/instant_confirm_dialog_gtk.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/instant_confirm_dialog_gtk.h"
 
 #include <gtk/gtk.h>
 
 #include "chrome/browser/instant/instant_confirm_dialog.h"
 #include "chrome/browser/instant/instant_controller.h"
@@ skipping 19 matching lines @@
     GtkWindow* parent, Profile* profile) : profile_(profile) {
   dialog_ = gtk_dialog_new_with_buttons(
       l10n_util::GetStringUTF8(IDS_INSTANT_OPT_IN_TITLE).c_str(),
       parent,
       static_cast<GtkDialogFlags>(GTK_DIALOG_MODAL | GTK_DIALOG_NO_SEPARATOR),
       GTK_STOCK_CANCEL, GTK_RESPONSE_REJECT,
       GTK_STOCK_OK, GTK_RESPONSE_ACCEPT,
       NULL);
   g_signal_connect(dialog_, "response", G_CALLBACK(OnResponseThunk), this);
 
-  GtkBox* vbox = GTK_BOX(GTK_DIALOG(dialog_)->vbox);
+  GtkBox* vbox = GTK_BOX(gtk_dialog_get_content_area(GTK_DIALOG(dialog_)));
   gtk_box_set_spacing(vbox, ui::kControlSpacing);
 
   GtkWidget* label = gtk_label_new(
       l10n_util::GetStringUTF8(IDS_INSTANT_OPT_IN_MESSAGE).c_str());
   gtk_label_set_line_wrap(GTK_LABEL(label), TRUE);
   gtk_box_pack_start(vbox, label, FALSE, FALSE, 0);
 
   GtkWidget* link_button = gtk_chrome_link_button_new(
       l10n_util::GetStringUTF8(IDS_LEARN_MORE).c_str());
   g_signal_connect(link_button, "clicked",
                    G_CALLBACK(OnLinkButtonClickedThunk), this);
 
-  GtkWidget* action_area = GTK_DIALOG(dialog_)->action_area;
+  GtkWidget* action_area = gtk_dialog_get_action_area(GTK_DIALOG(dialog_));
   gtk_container_add(GTK_CONTAINER(action_area), link_button);
   gtk_button_box_set_child_secondary(GTK_BUTTON_BOX(action_area),
                                      link_button,
                                      TRUE);
 
   gtk_dialog_set_default_response(GTK_DIALOG(dialog_), GTK_RESPONSE_ACCEPT);
   gtk_widget_show_all(dialog_);
 }
 
 InstantConfirmDialogGtk::~InstantConfirmDialogGtk() {
   gtk_widget_destroy(dialog_);
 }
 
 void InstantConfirmDialogGtk::OnResponse(GtkWidget* dialog, int response_id) {
   if (response_id == GTK_RESPONSE_ACCEPT)
     InstantController::Enable(profile_);
 
   delete this;
 }
 
 void InstantConfirmDialogGtk::OnLinkButtonClicked(GtkWidget* button) {
   // We open a new browser window so the Options dialog doesn't get lost behind
   // other windows.
   Browser* browser = Browser::Create(profile_);
   browser->AddSelectedTabWithURL(browser::InstantLearnMoreURL(),
                                  content::PAGE_TRANSITION_LINK);
   browser->window()->Show();
 }