Add VR_DISPLAY_MODE settings to be backed up.

Test: use adb backup to backup/restore and verify value is carried over.
Bug: 34437367
Change-Id: Icefc6bb1ae2f6410580214d0fe4fe4bd40038f46

core/java/android/provider/Settings.java

@@ -6992,7 +6992,8 @@ public final class Settings {
             DOZE_PULSE_ON_DOUBLE_TAP,
             NFC_PAYMENT_DEFAULT_COMPONENT,
             AUTOMATIC_STORAGE_MANAGER_DAYS_TO_RETAIN,
-            ASSIST_GESTURE_ENABLED
+            ASSIST_GESTURE_ENABLED,
+            VR_DISPLAY_MODE
         };
 
         /**

core/tests/coretests/src/android/provider/SettingsBackupTest.java

@@ -468,7 +468,6 @@ public class SettingsBackupTest {
                  Settings.Secure.USER_SETUP_COMPLETE,
                  Settings.Secure.VOICE_INTERACTION_SERVICE,
                  Settings.Secure.VOICE_RECOGNITION_SERVICE,
-                 Settings.Secure.VR_DISPLAY_MODE, // Candidate?
                  Settings.Secure.WEB_ACTION_ENABLED);
 
     @Test