async getContentHtml() {
    return new Promise((resolve, reject) => {
      this.contentResolve = resolve;
      this.contentReject = reject;
      this.sendAction(actions.content, 'postHtml');

      this.pendingContentHtml = setTimeout(() => {
        if (this.contentReject) {
          this.contentReject('timeout');
        }
      }, 5000);
    });
  }
@deprecated please use onChange
@returns {Promise}