code: function downloadManager_cleanAll(downloads) {
      // Cancel any active downloads
      this.cancelActiveDownloads();
  
      // If no downloads have been specified retrieve the list from the database
      if (downloads === undefined || downloads.length == 0)
        downloads = this.getAllDownloads();
      else
        downloads = downloads.concat(this.getAllDownloads());
  
      // Delete all files referred to in the Download Manager
      this.deleteDownloadedFiles(downloads);
  
      // Clean any entries from the Download Manager database
      this.cleanUp();
    }
docs: Cancel any active downloads, remove the files, and clean
  up the Download Manager database
  
  @param {Array of download} downloads
  Downloaded files which should be deleted (optional)