anchor.diff:      }));
     }
   
  -  void _setSignInStatus(bool isSignedIn) async {
  +  static void _setSignInStatus(bool isSignedIn) async {
       final user = _googleAuth.currentUser.get();
       final isAuthorized = user.hasGrantedScopes(_scope);
   
  
positive.code: import 'dart:js';
  
  import 'gapi.dart';
  import 'json_js.dart';
  import 'private_keys.dart' as key_store;
  
  class CredentialService {
    CredentialService._private();
  
    static final CredentialService _singleton = CredentialService._private();
  
    factory CredentialService() {
      return _singleton;
    }
  
    GoogleAuth _googleAuth;
    final _scope = 'https://www.googleapis.com/auth/display-video';
    final _redirectURI = 'http://localhost:8080';
  
    /// Loads gapi.client library and calls [_initClient]
    /// when library finishes loading.
  
negative.code:     }
    }
  
    static void _initClient() async {
      // Retrieve the discovery document for version 1 of DV360 public API.
      final discoveryUrl =
          'https://displayvideo.googleapis.com/\$discovery/rest?version=v1';
  