Slice background worker with Wi-Fi Slice

Test: manual

Change-Id: Ic4fdc5713f511ff80f03728c99c68fda3d0cab02

src/com/android/settings/slices/CustomSliceable.java

@@ -89,6 +89,16 @@ public interface CustomSliceable {
         return null;
     }
 
+    /**
+     * Settings Slices which can represent component lists that are updatable by the
+     * {@link SliceBackgroundWorker} returned here.
+     *
+     * @return a {@link SliceBackgroundWorker} for fetching the list of results in the background.
+     */
+    default SliceBackgroundWorker getBackgroundWorker() {
+        return null;
+    }
+
     /**
      * Standardize the intents returned to indicate actions by the Slice.
      * <p>