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

chrome/browser/ui/gtk/update_recommended_dialog.cc

Index: chrome/browser/ui/gtk/update_recommended_dialog.cc
diff --git a/chrome/browser/ui/gtk/update_recommended_dialog.cc b/chrome/browser/ui/gtk/update_recommended_dialog.cc
index 7941a2e9f4170d7f28922c369a446df7b371cc34..61984f621d5c6992c0a9ad8a08445a3d5e162fa7 100644
--- a/chrome/browser/ui/gtk/update_recommended_dialog.cc
+++ b/chrome/browser/ui/gtk/update_recommended_dialog.cc
@@ -39,8 +39,9 @@ UpdateRecommendedDialog::UpdateRecommendedDialog(GtkWindow* parent) {
                                 l10n_util::GetStringUTF16(IDS_PRODUCT_NAME)));
   GtkWidget* label = gtk_label_new(text.c_str());
   gtk_util::SetLabelWidth(label, kMessageWidth);
-  gtk_box_pack_start(GTK_BOX(GTK_DIALOG(dialog_)->vbox), label,
-                     FALSE, FALSE, 0);
+
+  GtkWidget* content_area = gtk_dialog_get_content_area(GTK_DIALOG(dialog_));
+  gtk_box_pack_start(GTK_BOX(content_area), label, FALSE, FALSE, 0);
 
   gtk_window_set_resizable(GTK_WINDOW(dialog_), FALSE);