Backup system QS tiles

Add QS tiles to the backup list.  Non-system tiles will get removed
since they won't be installed when restore happens.

Change-Id: Iccf6e773384c45bd4d1f10c21aa8af356b3920d2
Bug: 28782938
diff --git a/core/java/android/provider/Settings.java b/core/java/android/provider/Settings.java
index 00d9387..300deea 100755
--- a/core/java/android/provider/Settings.java
+++ b/core/java/android/provider/Settings.java
@@ -6311,6 +6311,12 @@
                 "system_navigation_keys_enabled";
 
         /**
+         * Holds comma separated list of ordering of QS tiles.
+         * @hide
+         */
+        public static final String QS_TILES = "sysui_qs_tiles";
+
+        /**
          * Whether preloaded APKs have been installed for the user.
          * @hide
          */
@@ -6396,7 +6402,8 @@
             NIGHT_DISPLAY_ACTIVATED,
             CAMERA_DOUBLE_TWIST_TO_FLIP_ENABLED,
             CAMERA_DOUBLE_TAP_POWER_GESTURE_DISABLED,
-            SYSTEM_NAVIGATION_KEYS_ENABLED
+            SYSTEM_NAVIGATION_KEYS_ENABLED,
+            QS_TILES,
         };
 
         /**