[gnome-chess/arnaudb/wip/gtk4: 13/27] Adapt to InfoBar API.

[Arnaud B. <arnaudb src gnome org>]

commit 2736fd4a4950c3bdbd036c989f1cdd9cb18556a1
Author: Arnaud Bonatti <arnaud bonatti gmail com>
Date:   Tue Apr 7 10:23:05 2020 +0200

    Adapt to InfoBar API.
    
    TODO test.

 src/gnome-chess.vala | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/src/gnome-chess.vala b/src/gnome-chess.vala
index 52cec23..ab9abc2 100644
--- a/src/gnome-chess.vala
+++ b/src/gnome-chess.vala
@@ -133,11 +133,11 @@ Copyright © 2015–2016 Sahil Sareen""";
 
     private void display_no_engine_info_bar ()
     {
-        var label = new Label (_("No chess engine is installed. You will not be able to play against the 
computer."));
+        var label = new Label (_("No chess engine is installed. You will not be able to play against the 
computer."));  // TODO init with label
         label.set_wrap (true);
         label.show ();
 
-        info_bar.get_content_area ().add (label);
+        info_bar.add_child (label);
         info_bar.set_message_type (MessageType.ERROR);
         info_bar.set_show_close_button (true);
         info_bar.response.connect (() => info_bar.destroy ());