Change WifiTrackerFactory methods to static.

/*

 * Copyright (C) 2017 The Android Open Source Project

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *      http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package com.android.settingslib.wifi;

import android.content.Context;

    private static WifiTracker sTestingWifiTracker;

    public void enableTestingMode() {

    public static void enableTestingMode() {

        sTestingMode = true;

    }

    public void disableTestingMode() {

    public static void disableTestingMode() {

        sTestingMode = false;

    }

    public void setTestingWifiTracker(WifiTracker tracker) {

    public static void setTestingWifiTracker(WifiTracker tracker) {

        sTestingWifiTracker = tracker;

    }