UsbDeviceManager: clean up HandlerThread creation

        // create a thread for our Handler

        HandlerThread thread = new HandlerThread("UsbDeviceManager",

                Process.THREAD_PRIORITY_BACKGROUND) {

            protected void onLooperPrepared() {

                mHandler = new UsbHandler();

            }

        };

                Process.THREAD_PRIORITY_BACKGROUND);

        thread.start();

        mHandler = new UsbHandler(thread.getLooper());

    }

    public void systemReady() {

        private static final int NOTIFICATION_INSTALLER = 3;

        private static final int NOTIFICATION_ADB = 4;

        public UsbHandler() {

        public UsbHandler(Looper looper) {

            super(looper);

            try {

                // persist.sys.usb.config should never be unset.  But if it is, set it to "adb"

                // so we have a chance of debugging what happened.