[gnome-panel] button-widget: avoid deprecated g_type_class_add_private

[Alberts Muktupāvels <muktupavels src gnome org>]

commit ab9e1571411f69a858511a5acbb0d9e70ab5ee23
Author: Alberts Muktupāvels <alberts muktupavels gmail com>
Date:   Thu Sep 13 16:40:21 2018 +0300

    button-widget: avoid deprecated g_type_class_add_private

 gnome-panel/button-widget.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)
---
diff --git a/gnome-panel/button-widget.c b/gnome-panel/button-widget.c
index 948fa2a2c..8d2eb9a1f 100644
--- a/gnome-panel/button-widget.c
+++ b/gnome-panel/button-widget.c
@@ -13,8 +13,6 @@
 #include "panel-util.h"
 #include "panel-typebuiltins.h"
 
-#define BUTTON_WIDGET_GET_PRIVATE(o) (G_TYPE_INSTANCE_GET_PRIVATE ((o), BUTTON_TYPE_WIDGET, 
ButtonWidgetPrivate))
-
 struct _ButtonWidgetPrivate {
        GtkIconTheme     *icon_theme;
        GdkPixbuf        *pixbuf;
@@ -45,7 +43,7 @@ enum {
 
 #define BUTTON_WIDGET_DISPLACEMENT 2
 
-G_DEFINE_TYPE (ButtonWidget, button_widget, GTK_TYPE_BUTTON)
+G_DEFINE_TYPE_WITH_PRIVATE (ButtonWidget, button_widget, GTK_TYPE_BUTTON)
 
 /* colorshift a pixbuf */
 static void
@@ -595,7 +593,7 @@ button_widget_init (ButtonWidget *button)
 {
        GtkStyleContext *context;
 
-       button->priv = BUTTON_WIDGET_GET_PRIVATE (button);
+       button->priv = button_widget_get_instance_private (button);
 
        button->priv->icon_theme = NULL;
        button->priv->pixbuf     = NULL;
@@ -625,8 +623,6 @@ button_widget_class_init (ButtonWidgetClass *klass)
        gobject_class->get_property = button_widget_get_property;
        gobject_class->set_property = button_widget_set_property;
 
-       g_type_class_add_private (klass, sizeof (ButtonWidgetPrivate));
-         
        widget_class->realize              = button_widget_realize;
        widget_class->unrealize            = button_widget_unrealize;
        widget_class->size_allocate        = button_widget_size_allocate;