code: function _handleDeleteFilter(e) {
          // Remove the filter set from the preferences and
          // clear the active filter set index from view state.
          var filterSets        = PreferencesManager.get("fileFilters") || [],
              activeFilterIndex = PreferencesManager.getViewState("activeFileFilter"),
              filterIndex       = $(e.target).parent().data("index") - FIRST_FILTER_INDEX;
  
          // Don't let the click bubble upward.
          e.stopPropagation();
  
          filterSets.splice(filterIndex, 1);
          PreferencesManager.set("fileFilters", filterSets);
  
          if (activeFilterIndex === filterIndex) {
              // Removing the active filter, so clear the active filter
              // both in the view state.
              setActiveFilter(null);
          } else if (activeFilterIndex > filterIndex) {
              // Adjust the active filter index after the removal of a filter set before it.
              --activeFilterIndex;
              setActiveFilter(filterSets[activeFilterIndex], activeFilterIndex);
          }
  
          _updatePicker();
          _doPopulate();
          _picker.refresh();
      }
docs: Remove the target item from the filter dropdown list and update dropdown button
  and dropdown list UI.
  @param {!Event} e Mouse events