设置默认桌面后，马上重启，有时出现无效的问题

设置默认桌面后，马上重启，有时出现无效，是因为设置后会延时10s才会将设置到结果保存到文件中。如下所示：
public void addPreferredActivity(IntentFilter filter, int match,
        ComponentName[] set, ComponentName activity, int userId) {
    addPreferredActivityInternal(filter, match, set, activity, true, userId,
            "Adding preferred");
}

private void addPreferredActivityInternal(IntentFilter filter, int match,
        ComponentName[] set, ComponentName activity, boolean always, int userId,
        String opname) {
    // writer
    int callingUid = Binder.getCallingUid();
    enforceCrossUserPermission(callingUid, userId, true, false, "add preferred activity");
    if (filter.countActions() == 0) {
        Slog.w(TAG, "Cannot set a preferred activity with no filter actions");
        return;
    }
    synchronized (mPackages) {
        if (mContext.checkCallingOrSelfPermission(
                android.Manifest.permission.SET_PREFERRED_APPLICATIONS)
                != PackageManager.PERMISSION_GRANTED) {
            if (getUidTargetSdkVersionLockedLPr(callingUid)
                    < Build.VERSION_CODES.FROYO) {
                Slog.w(TAG, "Ignoring addPreferredActivity() from uid "
                        + callingUid);
                return;
            }
            mContext.enforceCallingOrSelfPermission(
                    android.Manifest.permission.SET_PREFERRED_APPLICATIONS, null);
        }

        PreferredIntentResolver pir = mSettings.editPreferredActivitiesLPw(userId);
        Slog.i(TAG, opname + " activity " + activity.flattenToShortString() + " for user "
                + userId + ":");
        filter.dump(new LogPrinter(Log.INFO, TAG), "  ");
        pir.addFilter(new PreferredActivity(filter, match, set, activity, always));
        scheduleWritePackageRestrictionsLocked(userId);//保存到data/system/users/0/package-restrictions.xml文件中
    }
}

//10s后写入问题

void scheduleWritePackageRestrictionsLocked(int userId) {
    if (!sUserManager.exists(userId)) return;
    mDirtyUsers.add(userId);
    if (!mHandler.hasMessages(WRITE_PACKAGE_RESTRICTIONS)) {
        mHandler.sendEmptyMessageDelayed(WRITE_PACKAGE_RESTRICTIONS, WRITE_SETTINGS_DELAY);//WRITE_SETTINGS_DELAY = 10*1000;
    }
}

//写入data/system/users/0/package-restrictions.xml文件中

case WRITE_PACKAGE_RESTRICTIONS: {
    Process.setThreadPriority(Process.THREAD_PRIORITY_DEFAULT);
    synchronized (mPackages) {
        removeMessages(WRITE_PACKAGE_RESTRICTIONS);
        for (int userId : mDirtyUsers) {
            mSettings.writePackageRestrictionsLPr(userId);
        }
        mDirtyUsers.clear();
    }
    Process.setThreadPriority(Process.THREAD_PRIORITY_BACKGROUND);
} break;