seat: remove wlr_seat_validate_grab_serial()

It makes little sense to have a catch-all grab vaildation function,
considering that e.g. tablet tool implicit grabs are possible as well.
Besides, the function has always returned true anyway.

include/wlr/types/wlr_seat.h

@@ -693,12 +693,6 @@ void wlr_seat_touch_end_grab(struct wlr_seat *wlr_seat);
  */
 bool wlr_seat_touch_has_grab(struct wlr_seat *seat);
 
-/**
- * Check whether this serial is valid to start a grab action such as an
- * interactive move or resize.
- */
-bool wlr_seat_validate_grab_serial(struct wlr_seat *seat, uint32_t serial);
-
 /**
  * Check whether this serial is valid to start a pointer grab action.
  */

types/seat/wlr_seat.c

@@ -444,13 +444,6 @@ struct wlr_seat_client *wlr_seat_client_from_resource(
 	return wl_resource_get_user_data(resource);
 }
 
-bool wlr_seat_validate_grab_serial(struct wlr_seat *seat, uint32_t serial) {
-	// TODO
-	//return serial == seat->pointer_state.grab_serial ||
-	//	serial == seat->touch_state.grab_serial;
-	return true;
-}
-
 uint32_t wlr_seat_client_next_serial(struct wlr_seat_client *client) {
 	uint32_t serial = wl_display_next_serial(wl_client_get_display(client->client));
 	struct wlr_serial_ringset *set = &client->serials;

types/xdg_shell/wlr_xdg_toplevel.c

@@ -265,11 +265,6 @@ static void xdg_toplevel_handle_show_window_menu(struct wl_client *client,
 		return;
 	}
 
-	if (!wlr_seat_validate_grab_serial(seat->seat, serial)) {
-		wlr_log(WLR_DEBUG, "invalid serial for grab");
-		return;
-	}
-
 	struct wlr_xdg_toplevel_show_window_menu_event event = {
 		.toplevel = toplevel,
 		.seat = seat,
@@ -296,11 +291,6 @@ static void xdg_toplevel_handle_move(struct wl_client *client,
 		return;
 	}
 
-	if (!wlr_seat_validate_grab_serial(seat->seat, serial)) {
-		wlr_log(WLR_DEBUG, "invalid serial for grab");
-		return;
-	}
-
 	struct wlr_xdg_toplevel_move_event event = {
 		.toplevel = toplevel,
 		.seat = seat,
@@ -342,11 +332,6 @@ static void xdg_toplevel_handle_resize(struct wl_client *client,
 		return;
 	}
 
-	if (!wlr_seat_validate_grab_serial(seat->seat, serial)) {
-		wlr_log(WLR_DEBUG, "invalid serial for grab");
-		return;
-	}
-
 	struct wlr_xdg_toplevel_resize_event event = {
 		.toplevel = toplevel,
 		.seat = seat,