function getExpectedProviderWithCustomParameters(
    providerId, opt_customParameters) {
  var expectedProvider = firebaseui.auth.idp.getAuthProvider(providerId);
  // Set custom parameters if provided on the expected provider.
  if (opt_customParameters) {
    expectedProvider.setCustomParameters(opt_customParameters);
  }
  return expectedProvider;
}
@param {string} providerId The provider Id to initialize.
@param {?Object=} opt_customParameters The optional custom OAuth parameters
    to match if expected.
@return {!Object} The expected provider with custom parameters and no scopes.