touch: add frame event

include/wlr/types/wlr_touch.h

@@ -22,6 +22,7 @@ struct wlr_touch {
 		struct wl_signal up; // struct wlr_event_touch_up
 		struct wl_signal motion; // struct wlr_event_touch_motion
 		struct wl_signal cancel; // struct wlr_event_touch_cancel
+		struct wl_signal frame;
 	} events;
 
 	void *data;

types/wlr_touch.c

@@ -11,6 +11,7 @@ void wlr_touch_init(struct wlr_touch *touch,
 	wl_signal_init(&touch->events.up);
 	wl_signal_init(&touch->events.motion);
 	wl_signal_init(&touch->events.cancel);
+	wl_signal_init(&touch->events.frame);
 }
 
 void wlr_touch_destroy(struct wlr_touch *touch) {