Google Login in Ionic 4

auth.service.ts

  constructor(private afAuth: AngularFireAuth, private http: HTTP) {
    afAuth.authState.subscribe(user => {
      this.user = user;
    });
  }

  async signInWithGoogle(user) {
    return await this.afAuth.auth.signInAndRetrieveDataWithCredential(
      firebase.auth.GoogleAuthProvider.credential(user.idToken)
    );
  }

login.page.ts

 constructor(
    private router: Router,
    private formBuilder: FormBuilder,
    public authService: AuthService,
    private toastCtrl: ToastController,
    private http: HTTP,
    private httpAngular: Http,
    private platform: Platform,
    private gplus: GooglePlus,
    public alertController: AlertController,
    private facebook: Facebook,
    private linkedinService: LinkedinService,
    public loadingController: LoadingController
  ) {
  }
  
  googleLogin() {
    this.presentLoading();

    if (this.platform.is("cordova")) {
      this.nativeGoogleLogin()
        .then(userCredentials => {
          if (userCredentials["additionalUserInfo"].isNewUser) {
            let user = {
              name: userCredentials["user"].displayName,
              email: userCredentials["user"].email,
              profile: userCredentials["user"].photoURL,
              uid: userCredentials["user"].uid
            };
            this.sendDataToServer(user);
            // Do something with data ex: create document
          }
          this.loading.dismiss();
          this.router.navigateByUrl("home");
        })
        .catch(err => {
          this.loading.dismiss();
          this.showAlert("Error", "Something went wrong");
        });
    } else {
      // When ionic serve is used

      this.loginWithProvider("google");
    }
  }

 async nativeGoogleLogin() {
    try {
      const user = await this.gplus.login({
        webClientId: environment.webClientId,
        offline: true,
        scopes: "profile email"
      });

      return this.authService.signInWithGoogle(user);
    } catch (err) {
      return reject("Error");
    }
  }