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

chrome/browser/ui/gtk/instant_confirm_dialog_gtk.cc

Index: chrome/browser/ui/gtk/instant_confirm_dialog_gtk.cc
diff --git a/chrome/browser/ui/gtk/instant_confirm_dialog_gtk.cc b/chrome/browser/ui/gtk/instant_confirm_dialog_gtk.cc
index c16692dd1928fef702ab5f3f45e3ffc4956e2413..0f16b8b841102ccc1f1b3719ed918b589a7df995 100644
--- a/chrome/browser/ui/gtk/instant_confirm_dialog_gtk.cc
+++ b/chrome/browser/ui/gtk/instant_confirm_dialog_gtk.cc
@@ -37,7 +37,7 @@ InstantConfirmDialogGtk::InstantConfirmDialogGtk(
       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(
@@ -50,7 +50,7 @@ InstantConfirmDialogGtk::InstantConfirmDialogGtk(
   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,