googlePlusLogin.ts

googleLogin(): Promise<any> {
  return new Promise((resolve, reject) => { 
      this.googlePlus.login({
        'webClientId': '5351366995-npuh9q89gaoiagoc4jssqck26gorj7hh.apps.googleusercontent.com',
        'offline': true
      }).then( res => {
              const googleCredential = firebase.auth.GoogleAuthProvider
                  .credential(res.idToken);

              firebase.auth().signInWithCredential(googleCredential)
            .then( response => {
                console.log("Firebase success: " + JSON.stringify(response));
                resolve(response)
            });
      }, err => {
          console.error("Error: ", err)
          reject(err);
      });
    });
    }