Does Google Open ID work with Salesforce.com's login authentication?
Does Google Open ID work with authentication on the salesforce1 and other oauth2.0 clients?
NOTE: If using OpenID as a Single Sign-on method, then setup the OpenID Connect provider, and then check the box on the My Domain page. No SAML is required for Google Identity into Salesforce.
1) The Custom URL via the Salesforce1 app should point to the appropriate My Domain
2) If Multiple SAML and Auth. Providers are configured, ensure that these selections are appropriately listed on the Login Branding page | Authentication Service field.
3) OpenID is used in place of SAML
Please see below for configuration suggestions.