FingerprintServiceを読んで気になったこと

read-fingerprint-service.txt

http://tools.oesf.biz/android-MNC/xref/com/android/server/fingerprint/FingerprintService.java
=====
    532         @Override
    533         // Binder call
    534         public void authenticate(final IBinder token, final long opId, final int groupId,
    535                 final IFingerprintServiceReceiver receiver, final int flags, String opPackageName) {
    536             checkPermission(USE_FINGERPRINT);
    537             if (!canUserFingerPrint(opPackageName)) {
    538                 return;
    539             }
    540             mHandler.post(new Runnable() {
    541                 @Override
    542                 public void run() {
    543                     startAuthentication(token, opId, groupId, receiver, flags);
    544                 }
    545             });
    546         }
=====

authenticate()の536行目で
checkPermission(USE_FINGERPRINT);
した後で

=====
    367     private boolean canUserFingerPrint(String opPackageName) {
    368         checkPermission(USE_FINGERPRINT);
    369 
    370         return mAppOps.noteOp(AppOpsManager.OP_USE_FINGERPRINT, Binder.getCallingUid(),
    371                 opPackageName) == AppOpsManager.MODE_ALLOWED;
    372     }
=====

もう一度canUserFingerPrint(String)の中で何故か
checkPermission(USE_FINGERPRINT);
している。