As noted in MDL-58220, for sites that previously used the Google Drive repository, after upgrading you should have a OAuth 2 Google service created for you automatically with your old client ID and secret. 

However, after upgrading our testing instance of moodle.org to 3.3, I notice that although the Google Drive repository is still enabled, when you look at the settings there is no OAuth 2 service selected because a Google service hasn't been created.