Extend NotificationListenerService to support system use cases.

package android.service.notification;

import android.annotation.PrivateApi;

import android.annotation.SdkConstant;

import android.app.INotificationManager;

import android.app.Service;

import android.content.ComponentName;

import android.content.Context;

import android.content.Intent;

import android.os.IBinder;

import android.os.ServiceManager;

import android.util.Log;

import java.util.Comparator;

import java.util.HashMap;

/**

 * A service that receives calls from the system when new notifications are posted or removed.

 * <p>To extend this class, you must declare the service in your manifest file with

    private INotificationManager mNoMan;

    /** Only valid after a successful call to (@link registerAsService}. */

    private int mCurrentUser;

    /**

     * The {@link Intent} that must be declared as handled by the service.

     */

        return true;

    }

    /**

     * Directly register this service with the Notification Manager.

     *

     * <p>Only system services may use this call. It will fail for non-system callers.

     * Apps should ask the user to add their listener in Settings.

     *

     * @param componentName the component that will consume the notification information

     * @param currentUser the user to use as the stream filter

     * @hide

     */

    @PrivateApi

    public void registerAsSystemService(ComponentName componentName, int currentUser)

            throws RemoteException {

        if (mWrapper == null) {

            mWrapper = new INotificationListenerWrapper();

        }

        INotificationManager noMan = getNotificationInterface();

        noMan.registerListener(mWrapper, componentName, currentUser);

        mCurrentUser = currentUser;

    }

    /**

     * Directly unregister this service from the Notification Manager.

     *

     * <P>This method will fail for listeners that were not registered

     * with (@link registerAsService).

     * @hide

     */

    @PrivateApi

    public void unregisterAsSystemService() throws RemoteException {

        if (mWrapper != null) {

            INotificationManager noMan = getNotificationInterface();

            noMan.unregisterListener(mWrapper, mCurrentUser);

        }

    }

    private class INotificationListenerWrapper extends INotificationListener.Stub {

        @Override

        public void onNotificationPosted(StatusBarNotification sbn,