public auth2: any;
public googleInit() {
gapi.load('auth2', () => {
  this.auth2 = gapi.auth2.init({
    client_id: 'my-client id',
    scope: 'profile email'
  });
  this.attachSignin(document.getElementById('googleSignIn'));
});
}
public attachSignin(element:any) {
this.auth2.attachClickHandler(element, {},
  (googleUser:any) => {
    let profile = googleUser.getBasicProfile();

    this.login(profile.getEmail(),"", 'S')/*Calling login function*/
   },
  (error:any) => {
    //alert(JSON.stringify(error, undefined, 2));
  });
}

ngAfterViewInit(){
  this.googleInit();
}

login(userId: string, password: string, option: string) {
this.authenticationService.login(userId,password,option)
        .subscribe(
        data => {
            if (data.responseStatus) {
                this.isSignBtnDisbld=false;
                this.router.navigate(['/home']);
            } else {
                alert(data.errorMsg);

            }
        },
        error => {
            alert("Server Error");
        });
}