static createDrawingManager(map) {
    var drawingManager = new google.maps.drawing.DrawingManager({
      drawingControl: false,
      polygonOptions: {fillColor: '#ff0000', strokeColor: '#ff0000'}
    });
    drawingManager.setMap(map);
    return drawingManager;
  }
Creates a drawing manager for the passed-in map.
@param {google.maps.Map} map The map for which to create a drawing
    manager.
@return {google.maps.drawing.DrawingManager} A drawing manager for
    the given map.