Cannot test on Google OAuth 2.0 Playground

[elct9620]

I test it on Google OAuth 2.0 Playground https://developers.google.com/oauthplayground/

When I finished authorize, I request a access token, but I get 400 bad request.
And it didn't return any error message.

Another problem is I using before_filter :oauth_required but it cannot correct work for OAuth2.
I find the source code still using oauth1, will it update?