Update Settings together with generateChallenge/revokeChallenge

The internal implementation of generate/revoke in system_server is now
asynchronous. To keep existing clients working, the manager classes
introduce a blocking version of the generateChallenge calls. This change
updates Settings to use the backward-compatible blocking calls.

Bug: 157790417

Test: Enroll fingerprint/face
Test: After enrollment, toggle setFeature or do subsequent enrollment
      in face/fingerprint settings
Change-Id: Ib4dfdc5f12530b938ab9b1745f5a19cd9e2eceee

src/com/android/settings/biometrics/face/FaceSettings.java

@@ -205,7 +205,7 @@ public class FaceSettings extends DashboardFragment {
             // Generate challenge in onResume instead of onCreate, since FaceSettings can be
             // created while Keyguard is showing, in which case the resetLockout revokeChallenge
             // will invalidate the too-early created challenge here.
-            final long challenge = mFaceManager.generateChallenge();
+            final long challenge = mFaceManager.generateChallengeBlocking();
             ChooseLockSettingsHelper helper = new ChooseLockSettingsHelper(getActivity(), this);
 
             mConfirmingPassword = true;
@@ -266,10 +266,7 @@ public class FaceSettings extends DashboardFragment {
                 && !mConfirmingPassword) {
             // Revoke challenge and finish
             if (mToken != null) {
-                final int result = mFaceManager.revokeChallenge();
-                if (result < 0) {
-                    Log.w(TAG, "revokeChallenge failed, result: " + result);
-                }
+                mFaceManager.revokeChallenge();
                 mToken = null;
             }
             finish();