code: function oauth(httpRequest, httpResponse){
          var code = httpRequest.query.code,
              redirectUrl = _.has(grasshopper.config.identities, 'google') ? grasshopper.config.identities.google.redirectUrl : 'defaultRoute';
  
  
          grasshopper.auth('Google', { code: code })
              .then(function(token) {
  
                  httpRequest.session.token = new Buffer(token).toString('base64');
                  httpRequest.session.save(function() {
                      httpResponse.redirect(redirectUrl+'/'+ httpRequest.session.token);
                  });
  
  
              })
              .fail(function(err){
                  httpResponse.redirect(redirectUrl+'/error='+ err.message);
              });
      }
docs: Method will accept the oauth callback from google, run authentication, then redirect the user to the page that accepts the token.