Google Credential page is the place where you tell Google about the sites and web applications that you wish to use oAuth with.
Create an web application credentials with:
- Google Credentials 
- Atopia Credentials -console.developers.google.com
Also see:
In the restrictions section on the "Client ID for Web application" page you can specify multiple `Authorized redirect URIs`. This means we can use a single configuration for multiple wiki domains, should we choose. We can also add the locations of our login dialog as the `Authorized Javascript origins` should we choose.
In the Credentials view take a note of the `Client ID`, and `Client secret` - developers.google.com