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
return cert_db_->ImportUserCert(data);
}
bool CertificateManagerModel::ImportCACerts(
    const net::ScopedCERTCertificateList& certificates,
    net::NSSCertDatabase::TrustBits trust_bits,
    net::NSSCertDatabase::ImportCertFailureList* not_imported) {
  return cert_db_->ImportCACerts(certificates, trust_bits, not_imported);
}
bool CertificateManagerModel::ImportServerCert(
    const net::ScopedCERTCertificateList& certificates,
    net::NSSCertDatabase::TrustBits trust_bits,
    net::NSSCertDatabase::ImportCertFailureList* not_imported) {
  return cert_db_->ImportServerCert(certificates, trust_bits, not_imported);
}
bool CertificateManagerModel::SetCertTrust(
    CERTCertificate* cert,
    net::CertType type,
    net::NSSCertDatabase::TrustBits trust_bits) {
  return cert_db_->SetCertTrust(cert, type, trust_bits);
}
bool CertificateManagerModel::Delete(CERTCertificate* cert) {
  return cert_db_->DeleteCertAndKey(cert);
}
void CertificateManagerModel::DidGetCertDBOnUIThread(