Add the new settings page for lock screen notifs

Add a new empty settings page, which is flag-guarded. When the flag
is disabled, show the original Notifications on lock screen
tri-state switch, otherwise show the new page.

Bug: 367455695
Flag: com.android.server.notification.notification_lock_screen_settings
Test: atest LockScreenNotificationsPreferenceControllerTest

Change-Id: I8a81ad651626f39380767b2c9cfa2f1c19d0e7c5

src/com/android/settings/notification/LockScreenNotificationsPreferencePageController.java

@@ -0,0 +1,40 @@
+/*
+ * Copyright (C) 2024 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.notification;
+
+import android.content.Context;
+
+import com.android.server.notification.Flags;
+import com.android.settings.core.BasePreferenceController;
+
+// TODO(b/367455695): remove controller when the feature flag is removed!
+
+/**
+ * Controller for lock screen notifications settings page.
+ */
+public class LockScreenNotificationsPreferencePageController extends BasePreferenceController {
+
+    public LockScreenNotificationsPreferencePageController(Context context, String preferenceKey) {
+        super(context, preferenceKey);
+    }
+
+    @Override
+    public int getAvailabilityStatus() {
+        return Flags.notificationLockScreenSettings() ? AVAILABLE : CONDITIONALLY_UNAVAILABLE;
+    }
+
+}