/**
 *
 * browser's default setTimeout is not reliable when
 * 1. tabs are inactive (Chrome verified)
 * 2. os goes to sleep
 *
 * this service ATTEMPS to negate these situations.
 *
 */
import { NgZone } from '@angular/core';
import { Observable } from 'rxjs';
import { AngularFireDatabase } from '@angular/fire/database';
export declare class TimerService {
    db: AngularFireDatabase;
    private zone;
    private tickEvent;
    serverTimeOffset: number;
    constructor(db: AngularFireDatabase, zone: NgZone);
    setTimeout(timeDiff: number): Observable<any>;
    fetchServerTimeOffset(): Observable<number>;
}