[DeviceService] Move //device/nfc to be part of the internal impl of Device Service

device/nfc/public/java/src/org/chromium/device/nfc/NfcDelegate.java

-// Copyright 2017 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-package org.chromium.device.nfc;
-
-import android.app.Activity;
-
-import org.chromium.base.Callback;
-
-/** Interface that allows the NFC implementation to access the Activity associated with a given
- * client. |hostId| is the same ID passed in NFCProvider::GetNFCForHost().
- */
-public interface NfcDelegate {
-    /** Calls |callback| with the Activity associated with |hostId|, and subsequently calls
-     * |callback| again whenever the Activity associated with |hostId| changes.
-     */
-    void trackActivityForHost(int hostId, Callback<Activity> callback);
-
-    /** Called when the NFC implementation no longer needs to track the Activity associated with
-     * |hostId|.
-     */
-    void stopTrackingActivityForHost(int hostId);
-}