code: function(bounds, mapSize) {
      var z = this.getBoundsZoom(bounds, mapSize);
      if(z === null) {
        return;
      }
  
      // project -> calculate center -> unproject
      var swPoint = cdb.geo.Map.latlngToMercator(bounds[0], z);
      var nePoint = cdb.geo.Map.latlngToMercator(bounds[1], z);
  
      var center = cdb.geo.Map.mercatorToLatLng({
        x: (swPoint[0] + nePoint[0])*0.5,
        y: (swPoint[1] + nePoint[1])*0.5
      }, z);
      this.set({
        center: center,
        zoom: z
      })
    }
docs: set center and zoom according to fit bounds