code: function commitPicker(picker) {
          var filter = getActiveFilter();
          return (filter && filter.patterns.length) ? compile(filter.patterns) : "";
      }
docs: Marks the filter picker's currently selected item as most-recently used, and returns the corresponding
  'compiled' filter object ready for use with filterPath().
  @param {!jQueryObject} picker UI returned from createFilterPicker()
  @return {!string} 'compiled' filter that can be passed to filterPath()/filterFileList().