fix the issue widget id can be wrong after restore

Bug: 171774227
Test: manual testing
1. randomly add/remove widgets to workspace
2. create a backup (Settings > System > Backup)
3. reset the device
4. restore from the backup
5. verify all of the widgets are restored properly

Change-Id: Id65e474dd9349aca715d7e6b88f8d58bc63066ae
diff --git a/src/com/android/launcher3/LauncherSettings.java b/src/com/android/launcher3/LauncherSettings.java
index d2758f5..fe423ed 100644
--- a/src/com/android/launcher3/LauncherSettings.java
+++ b/src/com/android/launcher3/LauncherSettings.java
@@ -121,6 +121,12 @@
                 + LauncherProvider.AUTHORITY + "/" + TABLE_NAME);
 
         /**
+         * The content:// style URL for "favorites_bakup" table
+         */
+        public static final Uri BACKUP_CONTENT_URI = Uri.parse("content://"
+                + LauncherProvider.AUTHORITY + "/" + BACKUP_TABLE_NAME);
+
+        /**
          * The content:// style URL for "favorites_preview" table
          */
         public static final Uri PREVIEW_CONTENT_URI = Uri.parse("content://"