code: function _removeFileFromMRU(paneId, file) {
          var index,
              compare = function (record) {
                  return (record.file === file && record.paneId === paneId);
              };
  
          // find and remove all instances
          do {
              index = _.findIndex(_mruList, compare);
              if (index !== -1) {
                  _mruList.splice(index, 1);
              }
          } while (index !== -1);
      }
docs: Removes a file from the global MRU list. Future versions of this
  implementation may support the ALL_PANES constant but FOCUS_PANE is not allowed
  @param {!string} paneId - Must be a valid paneId (not a shortcut e.g. ALL_PANES)
  @ @param {File} file The file object to remove.
  @private