ntSandboxPref() {
    const observer = {
      observe() {
        const level = Services.prefs.getIntPref(
          "security.sandbox.content.level",
          -1
        );
        if (level === 0) {
          const winEnum = Services.wm.getEnumerator("navigator:browser");
          while (winEnum.hasMoreElements()) {
            const win = winEnum.getNext();
            SandboxUtils.maybeWarnAboutDisabledContentSandbox(win);
          }
          Services.prefs.removeObserver(
            "security.sandbox.content.level",
            observer
          );
        }
      },
    };
    Services.prefs.addObserver("security.sandbox.content.level", observer);
  },
};
PK