In fact, The document you've read has answered you question:
When you create a client ID in the Google Developers Console, two redirect_uris are created for you:
urn:ietf:wg:oauth:2.0:oob
andhttp://localhost
. The value your application uses determines how the authorization code is returned to your application.
http://localhost
signals to the Google Authorization Server that the authorization code should be returned as a query string parameter to the web server on the client. You may specify a port number without changing the Google Developers Console configuration.