gtk: Use gtk_dialog_get_content_area() throughout.

chrome/browser/ui/gtk/importer/import_lock_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/importer/import_lock_dialog_gtk.h"
 
 #include <gtk/gtk.h>
 
 #include "base/message_loop.h"
 #include "chrome/browser/importer/importer_host.h"
@@ skipping 29 matching lines @@
       (GtkDialogFlags) (GTK_DIALOG_MODAL | GTK_DIALOG_NO_SEPARATOR),
       NULL);
 
   gtk_util::AddButtonToDialog(dialog_,
       l10n_util::GetStringUTF8(IDS_IMPORTER_LOCK_CANCEL).c_str(),
       GTK_STOCK_CANCEL, GTK_RESPONSE_REJECT);
   gtk_util::AddButtonToDialog(dialog_,
       l10n_util::GetStringUTF8(IDS_IMPORTER_LOCK_OK).c_str(),
       GTK_STOCK_OK, GTK_RESPONSE_ACCEPT);
 
-  GtkWidget* content_area = GTK_DIALOG(dialog_)->vbox;
+  GtkWidget* content_area = gtk_dialog_get_content_area(GTK_DIALOG(dialog_));
   gtk_box_set_spacing(GTK_BOX(content_area), gtk_util::kContentAreaSpacing);
   GtkWidget* label = gtk_label_new(
       l10n_util::GetStringUTF8(IDS_IMPORTER_LOCK_TEXT).c_str());
   gtk_label_set_line_wrap(GTK_LABEL(label), TRUE);
   gtk_box_pack_start(GTK_BOX(content_area), label, FALSE, FALSE, 0);
 
   g_signal_connect(dialog_, "response", G_CALLBACK(OnResponseThunk), this);
   gtk_window_set_resizable(GTK_WINDOW(dialog_), FALSE);
   gtk_widget_show_all(dialog_);
 }
 
 ImportLockDialogGtk::~ImportLockDialogGtk() {}
 
 void ImportLockDialogGtk::OnResponse(GtkWidget* dialog, int response_id) {
   if (response_id == GTK_RESPONSE_ACCEPT) {
     MessageLoop::current()->PostTask(FROM_HERE, NewRunnableMethod(
         importer_host_.get(), &ImporterHost::OnImportLockDialogEnd, true));
   } else {
     MessageLoop::current()->PostTask(FROM_HERE, NewRunnableMethod(
         importer_host_.get(), &ImporterHost::OnImportLockDialogEnd, false));
   }
   gtk_widget_destroy(dialog_);
   delete this;
 }