Angularfire injectable provider

af.ts

import {Injectable} from "@angular/core";
import { Observable } from 'rxjs/Observable';
import { FirebaseObjectFactoryOpts } from "angularfire2/interfaces";
import { AngularFireDatabaseModule, AngularFireDatabase, FirebaseListObservable, FirebaseObjectObservable } from 'angularfire2/database';
import { AngularFireAuthModule, AngularFireAuth } from 'angularfire2/auth';
import * as firebase from 'firebase/app';
import { Headers, Http, RequestOptions } from '@angular/http';
import 'rxjs/add/operator/toPromise';

@Injectable()
export class AF {
  public messages: FirebaseListObservable<any>;
  public users: FirebaseListObservable<any>;
  public displayName: string;
  public email: string;
  public user: FirebaseListObservable<any>;
  private beTokenUrl = 'http://localhost:8081/get-token';
  private verifyTokenUrl = 'http://localhost:8081/verifyIdToken';
  private authApiUrl = 'http://localhost:8081/api/hello';
  private createUserUrl = 'http://localhost:8081/create-user';
  public clientToken: string;
  private tokenID: string;

  constructor(public afAuth: AngularFireAuth, public db: AngularFireDatabase, private http: Http) {
    this.afAuth.authState.subscribe(res => {
      if (res && res.uid) {
        console.log('user is logged in', res);
        this.user = db.list('users/' + res.uid);
        console.log('this.user', this.user);
      } else {
        console.log('user not logged in');
      }
    });
  }

  createNewUser(email, password) {
    this.http.post(this.createUserUrl, {emailAddress: email, pass: password})
    .toPromise()
    .then(function (res) {
      console.log('createNewUser success', res.json());
    })
    .catch(function(error) {
      console.log('createNewUser error', error);
    });
  } ...