Using the OAuth2Client form https://github.com/mj1856/DotNetOpenAuth.GoogleOAuth2/tree/master/DotNetOpenAuth.GoogleOAuth2

GoogleOAuth.Snippet.cs

// Setup OAuthClient for Google
if (!string.IsNullOrWhiteSpace(ConfigurationManager.AppSettings["GoogleAppId"]) && !string.IsNullOrWhiteSpace(ConfigurationManager.AppSettings["GoogleAppSecret"]))
{
    OAuthWebSecurity.RegisterClient(new GoogleOAuth2Client(ConfigurationManager.AppSettings["GoogleAppId"], ConfigurationManager.AppSettings["GoogleAppSecret"]), "Google", extraData); 
}