displayFailure_(error) {
    var errorDiv = goog.dom.getElement(constants.ElementId.ERROR_DIV);
    if (error) {
      var errorMsg = error.messageId !== undefined ?
          chrome.i18n.getMessage(error.messageId) :
          error.message;
      utils.errorHandler(error);
      errorDiv.textContent = errorMsg;
    } else {
      errorDiv.textContent = '';
    }
  }
Displays an error message to the user.
@param {Error} error The error to display.
@private