[gtkmm] gtk_extra_objects.defs: Add GtkGridView

[Kjell Ahlstedt <kjellahl src gnome org>]

commit 6c3c087cd90ab119bf062c0ebe4d66b143b1ee21
Author: Kjell Ahlstedt <kjellahlstedt gmail com>
Date:   Mon Sep 7 10:04:42 2020 +0200

    gtk_extra_objects.defs: Add GtkGridView

 gtk/src/gtk_extra_objects.defs | 6 ++++++
 1 file changed, 6 insertions(+)
---
diff --git a/gtk/src/gtk_extra_objects.defs b/gtk/src/gtk_extra_objects.defs
index 536b772d..218500f7 100644
--- a/gtk/src/gtk_extra_objects.defs
+++ b/gtk/src/gtk_extra_objects.defs
@@ -280,6 +280,12 @@
   (gtype-id "GTK_TYPE_GRID_LAYOUT")
 )
 
+(define-object GridView
+  (in-module "Gtk")
+  (c-name "GtkGridView")
+  (gtype-id "GTK_TYPE_GRID_VIEW")
+)
+
 (define-object HeaderBar
   (in-module "Gtk")
   (c-name "GtkHeaderBar")