gtk: Use gtk_dialog_get_content_area() throughout.

chrome/browser/ui/gtk/importer/import_progress_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_progress_dialog_gtk.h"
 
 #include <gtk/gtk.h>
 
 #include <string>
 
@@ skipping 63 matching lines @@
   // Build the dialog.
   dialog_ = gtk_dialog_new_with_buttons(
       l10n_util::GetStringUTF8(IDS_IMPORT_PROGRESS_TITLE).c_str(),
       parent_,
       (GtkDialogFlags) (GTK_DIALOG_MODAL | GTK_DIALOG_NO_SEPARATOR),
       GTK_STOCK_CANCEL,
       GTK_RESPONSE_REJECT,
       NULL);
   importer_host_->set_parent_window(GTK_WINDOW(dialog_));
 
-  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* control_group = gtk_vbox_new(FALSE, gtk_util::kControlSpacing);
 
   GtkWidget* import_info = gtk_label_new(
       l10n_util::GetStringFUTF8(IDS_IMPORT_PROGRESS_INFO,
                                 importer_name).c_str());
   gtk_util::SetLabelWidth(import_info, 400);
   gtk_box_pack_start(GTK_BOX(control_group), import_info, FALSE, FALSE, 0);
 
@@ skipping 129 matching lines @@
                               const SourceProfile& source_profile,
                               Profile* profile,
                               bool first_run) {
   DCHECK_NE(0, items);
   ImportProgressDialogGtk::StartImport(
       parent, items, importer_host, importer_observer, source_profile, profile,
       first_run);
 }
 
 }  // namespace importer