I can help you in fixing your error related to Google.
The easiest way to fix your issue is as below
Go to Settings in your Chrome then you need to go to Content Settings and simply Uncheck Block third-party cookies and site data.
If above solution is not working for you then you can use below approach
Validating your token may work before using your token each time but it may add some extra overhead for the rare use-case when each time we try to load your picker and if calling your API endpoints with the use of token after you try to re-authenticate issue and there was no key about the token being invalid. Then you can try to validate your token by simply making the web service request to the endpoint on a Google Authorization Server and then you can perform the string match on a results of your web service request.