function loadPickerApi() {
    if (!wtf.io.drive.filePickerLoadResult_) {
      wtf.io.drive.filePickerLoadResult_ = new goog.result.SimpleResult();
      google.load('picker', '1', {
        'callback': function() {
          wtf.io.drive.filePickerLoadResult_.setValue(true);
        }
      });
    }
    goog.result.wait(wtf.io.drive.filePickerLoadResult_, show);
  }
Shows a file picker.
{@see #prepare} must have been called and completed before this can
be used.
@param {{
  title: string
}} options Picker options.
@return {!goog.result.Result} Async result. The value will be a list of
    ['file name', 'file id'] tuples.