code: function expandFileGlobs(filesAndPatterns, rootDir, callbackFn) {
    fileMatcher.resolveAnyGlobPatternsAsync(filesAndPatterns, rootDir)
        .then(function(result) { callbackFn(null, result); })
        .fail(callbackFn);
  }
docs: As an exported convenience function, expands all glob patterns in the given
  list of filesAndPatterns into the list of matched files.
  @param {!Array.<string>} filesAndPatterns List of files and file patterns,
  e.g. ['my/single/file.js', 'dir/of/*.js'].
  @param {string} rootDir Root directory that filesAndPatterns are relative to.
  @param {function(Error, Array.<string>=)} callbackFn Called with the list of
  expanded files on success, or an Error on failure.