It's going to be removed from Chromium, see https://crbug.com/812523.

/cc @electron/code-owners 
chromium_src/chrome/browser/certificate_manager_model.cc
const CreationCallback& callback) {
  DCHECK_CURRENTLY_ON(BrowserThread::UI);
  base::PostTask(
      FROM_HERE, {BrowserThread::IO},
      base::BindOnce(&CertificateManagerModel::GetCertDBOnIOThread,
                     browser_context->GetResourceContext(), callback));
}
CertificateManagerModel::CertificateManagerModel(
    net::NSSCertDatabase* nss_cert_database,
    bool is_user_db_available)
    : cert_db_(nss_cert_database), is_user_db_available_(is_user_db_available) {
  DCHECK_CURRENTLY_ON(BrowserThread::UI);
}
CertificateManagerModel::~CertificateManagerModel() = default;
int CertificateManagerModel::ImportFromPKCS12(
    PK11SlotInfo* slot_info,
    const std::string& data,
    const base::string16& password,
    bool is_extractable,
    net::ScopedCERTCertificateList* imported_certs) {
  return cert_db_->ImportFromPKCS12(slot_info, data, password, is_extractable,
                                    imported_certs);
}
int CertificateManagerModel::ImportUserCert(const std::string& data) {