code: function(done) {
      var self = this;
      this.fire('updated');
      this.fire('loading');
      var map = this.options.map;
  
      this.getTiles(function(urls, err) {
        if(urls) {
          self.tilejson = urls;
          self.setUrl(self.tilejson.tiles[0]);
          // manage interaction
          self._reloadInteraction();
          self.ok && self.ok();
          done && done();
        } else {
          self.error && self.error(err);
          done && done();
        }
      });
    }
docs: Update CartoDB layer
  generates a new url for tiles and refresh leaflet layer
  do not collide with leaflet _update