Update FaceSettings to match mocks

Settings page should not show if device credential is not confirmed

Bug: 111548037
Fixes: 116531896

Test: adb shell settings get secure face_unlock_app_enabled
Test: make -j56 RunSettingsRoboTests

Change-Id: I651ee88e9ee4017ee3dc52fa8a5d05cb8f092e1d

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

@@ -0,0 +1,65 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License
+ */
+
+package com.android.settings.biometrics.face;
+
+import static android.provider.Settings.Secure.FACE_UNLOCK_APP_ENABLED;
+
+import android.content.Context;
+import android.provider.Settings;
+
+import com.android.settings.core.TogglePreferenceController;
+
+/**
+ * Preference controller for Face settings page controlling the ability to use
+ * Face authentication in apps (through BiometricPrompt).
+ */
+public class FaceSettingsAppPreferenceController extends TogglePreferenceController {
+
+    private static final String KEY = "security_settings_face_app";
+
+    private static final int ON = 1;
+    private static final int OFF = 0;
+    private static final int DEFAULT = ON;  // face unlock is enabled for BiometricPrompt by default
+
+    public FaceSettingsAppPreferenceController(Context context, String preferenceKey) {
+        super(context, preferenceKey);
+    }
+
+    public FaceSettingsAppPreferenceController(Context context) {
+        this(context, KEY);
+    }
+
+    @Override
+    public boolean isChecked() {
+        if (!FaceSettings.isAvailable(mContext)) {
+            return false;
+        }
+        return Settings.Secure.getInt(
+                mContext.getContentResolver(), FACE_UNLOCK_APP_ENABLED, DEFAULT) == ON;
+    }
+
+    @Override
+    public boolean setChecked(boolean isChecked) {
+        return Settings.Secure.putInt(mContext.getContentResolver(), FACE_UNLOCK_APP_ENABLED,
+                isChecked ? ON : OFF);
+    }
+
+    @Override
+    public int getAvailabilityStatus() {
+        return AVAILABLE;
+    }
+}