code: function _makePaneMostRecent(paneId) {
          var pane = _getPane(paneId);
  
          if (pane.getCurrentlyViewedFile()) {
              _makeFileMostRecent(paneId, pane.getCurrentlyViewedFile());
          }
      }
docs: Makes the Pane's current file the most recent
  @param {!string} paneId - id of the pane to make the file most recent, or ACTIVE_PANE
  @param {!File} file - File object to make most recent
  @private