core: add and use nm_keep_alive_destroy()

When we are done with a NMKeepAlive instance, we always should do
three things:

  - unset the owner
  - disarm (freeze) the keep-alive
  - give up our reference.

Add and use nm_keep_alive_destroy() that does this.

src/nm-active-connection.c

@@ -1533,8 +1533,7 @@ finalize (GObject *object)
 
 	nm_dbus_track_obj_path_set (&priv->settings_connection, NULL, FALSE);
 
-	_nm_keep_alive_set_owner (priv->keep_alive, NULL);
+	nm_clear_pointer (&priv->keep_alive, nm_keep_alive_destroy);
-	g_clear_object (&priv->keep_alive);
 
 	G_OBJECT_CLASS (nm_active_connection_parent_class)->finalize (object);
 }

src/nm-keep-alive.c

@@ -385,6 +385,26 @@ nm_keep_alive_disarm (NMKeepAlive *self)
 	cleanup_dbus_watch (self);
 }
 
+/**
+ * nm_keep_alive_destroy:
+ * @self: (allow-none): the #NMKeepAlive instance to destroy.
+ *
+ * This does 3 things in one:
+ *
+ *   - set owner to %NULL
+ *   - disarm the instance.
+ *   - unref @self.
+ */
+void
+nm_keep_alive_destroy (NMKeepAlive *self)
+{
+	if (!self)
+		return;
+	_nm_keep_alive_set_owner (self, NULL);
+	nm_keep_alive_disarm (self);
+	g_object_unref (self);
+}
+
 /*****************************************************************************/
 
 static void

src/nm-keep-alive.h

@@ -43,6 +43,8 @@ gboolean nm_keep_alive_is_alive (NMKeepAlive *self);
 void nm_keep_alive_arm (NMKeepAlive *self);
 void nm_keep_alive_disarm (NMKeepAlive *self);
 
+void nm_keep_alive_destroy (NMKeepAlive *self);
+
 void nm_keep_alive_set_settings_connection_watch_visible (NMKeepAlive         *self,
                                                           NMSettingsConnection *connection);