Discovery (oauth2client) to GData OAuth2Token converter. Blatantly taken from http://blog.bossylobster.com/2012_12_01_archive.html (Thanks!)

oauth2tokenfromcredentials.py

class OAuth2TokenFromCredentials(OAuth2Token):
    def __init__(self, credentials):
        self.credentials = credentials
        super(OAuth2TokenFromCredentials, self).__init__(None, None, None, None)
        self.UpdateFromCredentials()

    def UpdateFromCredentials(self):
        self.client_id = self.credentials.client_id
        self.client_secret = self.credentials.client_secret
        self.user_agent = self.credentials.user_agent
        self.token_uri = self.credentials.token_uri
        self.access_token = self.credentials.access_token
        self.refresh_token = self.credentials.refresh_token
        self.token_expiry = self.credentials.token_expiry
        self._invalid = self.credentials.invalid

    def generate_authorize_url(self, *args, **kwargs): raise NotImplementedError
    def get_access_token(self, *args, **kwargs): raise NotImplementedError
    def revoke(self, *args, **kwargs): raise NotImplementedError
    def _extract_tokens(self, *args, **kwargs): raise NotImplementedError

    def _refresh(self, unused_request):
        self.credentials._refresh(Http().request)
        self.UpdateFromCredentials()