anchor.diff:  typedef OnSignInCallback(SimpleOAuth2 authenticationContext);
   typedef OnSignOutCallback();
   
  +void enableSignInUI(bool isAnonymous) {
  +  Element el;
  +  
  +  el = query(".welcome");
  +  if (el != null) {
  +    el.hidden = isAnonymous;
  +  }
  +  
  +  el = query("#disconnect");
  +  if (el != null) {
  +    el.hidden = isAnonymous;
  +  }
  +  
  +  el = query("#google-connect");
  +  if (el != null) {
  +    el.hidden = !isAnonymous;
  +  }
  +}
  +
   class LoginPanel extends WebComponent {
     OnSignInCallback signInCallback;
     OnSignOutCallback signOutCallback;
  
positive.code:       }
      } else if (authResult["error"] != null) {
        print("There was an error: ${authResult["error"]}");
        query("#google-connect").style.display = "block";
        query("#auth-disconnect").style.display = "none";
      }
    }
  
    /**
     * Calls the OAuth2 endpoint to disconnect the app for the user.
     */
  
negative.code:     print("authRequest = ${authResult}");
  
      if (authResult["access_token"] != null) {
        enableSignInUI(false);
  
        // Enable Authenticated requested with the granted token in the client libary
        authenticationContext.token = authResult["access_token"];
  