@Override
    protected String doInBackground(Void... params) {
      DriveHelper helper = new DriveHelper(mGoogleApiClient);
      StringBuilder result = new StringBuilder();
      MetadataBuffer buffer =
          Drive.DriveApi.getAppFolder(mGoogleApiClient)
              .listChildren(mGoogleApiClient)
              .await()
              .getMetadataBuffer();
      try {
        result
            .append("found ")
            .append(buffer.getCount())
            .append(" file(s):")
            .append(EOL)
            .append("----------")
            .append(EOL);

        for (Metadata m : buffer) {
          DriveId id = m.getDriveId();
          result.append("Name: ").append(m.getTitle()).append(EOL);
          result.append("MimeType: ").append(m.getMimeType()).append(EOL);
          result.append(id.encodeToString()).append(EOL);
          result.append("LastModified: ").append(m.getModifiedDate().getTime()).append(EOL);
          String content = helper.getContentsFromDrive(id);
          result.append("--------").append(EOL).append(content).append(EOL);
          result.append("--------");
        }
      } catch (IOException io) {
        result.append("Exception fetching content").append(EOL);
      } finally {
        buffer.close();
      }
      return result.toString();
    }