1. override
bool shouldRelayout(MaxTileWidthGridDelegate oldDelegate)

Override this method to return true when the children need to be laid out.

Source 

@override
bool shouldRelayout(MaxTileWidthGridDelegate oldDelegate) {
  return maxTileWidth != oldDelegate.maxTileWidth
      || tileAspectRatio != oldDelegate.tileAspectRatio
      || super.shouldRelayout(oldDelegate);
}