Peta Google Android. tunggu inisialisasi lokasi sebelum memindahkan kamera Maps

Saya memiliki kode berikut di aplikasi saya (tujuannya adalah untuk memiliki fragmen GoogleMaps):

import android.Manifest;
import android.app.Activity;
import android.content.Context;
import android.content.pm.PackageManager;
import android.location.Criteria;
import android.location.Location;
import android.location.LocationManager;
import android.net.Uri;
import android.os.Bundle;
import android.support.v4.app.ActivityCompat;
import android.widget.ArrayAdapter;
import android.widget.Toast;
import com.google.android.gms.appindexing.Action;
import com.google.android.gms.appindexing.AppIndex;
import com.google.android.gms.appindexing.Thing;
import com.google.android.gms.common.api.GoogleApiClient;
import com.google.android.gms.location.LocationListener;
import com.google.android.gms.location.LocationServices;
import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.MapFragment;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.MarkerOptions;
import java.util.HashMap;
import java.util.List;

public class MapsActivity extends Activity implements LocationListener {

private GoogleMap mMap;        

private static final LatLng position_gps = new LatLng([defined,position]);
int MY_PERMISSIONS_REQUEST_FINE_LOCATION;

private static final LatLng position_gps_track1 = new LatLng([something], [something]);

/**
 * ATTENTION: This was auto-generated to implement the App Indexing API.
 * See https://g.co/AppIndexing/AndroidStudio for more information.
 */
private GoogleApiClient client;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_maps);
    LocationManager locationManager;

    if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION)
            != PackageManager.PERMISSION_GRANTED
            && ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION)
            != PackageManager.PERMISSION_GRANTED) {
        ActivityCompat.requestPermissions(this,
                new String[]{Manifest.permission.ACCESS_FINE_LOCATION},
                MY_PERMISSIONS_REQUEST_FINE_LOCATION);
        return;
    }
    locationManager = (LocationManager) getSystemService(LOCATION_SERVICE);
    String provider = locationManager.getBestProvider(new Criteria(), true);
    Location location = locationManager.getLastKnownLocation(provider);
    mMap = ((MapFragment) getFragmentManager().findFragmentById(R.id.map)).getMap();
    if (mMap != null) {
        mMap.addMarker(new MarkerOptions().position(position_gps_track1).title("T1 - Thomas"));

        LatLng pos_gps;
        if (location == null) {    
            pos_gps = position_gps;     
        } else {                    
            pos_gps = new LatLng(location.getLatitude(), location.getLongitude());
        }
        mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(pos_gps, 15));
        mMap.animateCamera(CameraUpdateFactory.zoomTo(15), 2000, null);
        mMap.setMyLocationEnabled(true);                       
        mMap.getUiSettings().setCompassEnabled(true);          
        mMap.getUiSettings().setZoomControlsEnabled(true);    
    } else {
        Toast.makeText(this, "Services GoogleMap indisponibles!", Toast.LENGTH_SHORT).show();
    }

    client = new GoogleApiClient.Builder(this).addApi(AppIndex.API).addApi(LocationServices.API).build();


}

@Override
public void onLocationChanged(Location location) {

    int latitude = (int) (location.getLatitude());
    int longitude = (int) (location.getLongitude());
    LatLng position_gps = new LatLng(location.getLatitude(), location.getLongitude());
    mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(position_gps, 15));
}


public Action getIndexApiAction() {
    Thing object = new Thing.Builder()
            .setName("Maps Page") // TODO: Define a title for the content shown.
            // TODO: Make sure this auto-generated URL is correct.
            .setUrl(Uri.parse("http://[ENTER-YOUR-URL-HERE]"))
            .build();
    return new Action.Builder(Action.TYPE_VIEW)
            .setObject(object)
            .setActionStatus(Action.STATUS_TYPE_COMPLETED)
            .build();
}

@Override
public void onStart() {
    super.onStart();
    client.connect();
    AppIndex.AppIndexApi.start(client, getIndexApiAction());
}

@Override
public void onStop() {
    super.onStop();
    AppIndex.AppIndexApi.end(client, getIndexApiAction());
    client.disconnect();
}
}

Saya ingin membuat peta fokus pada lokasi saat ini ketika aktivitas dimulai tetapi, pada metode onCreate(), variabel lokasi selalu nol, dan peta fokus pada lokasi yang saya tentukan.

Tolong, bagaimana cara memastikan bahwa, ketika lokasi akhirnya diinisialisasi, peta akan memperbesar lokasi saya saat ini?

Terima kasih.