Fix the consistency of connection status displayed on Wi-Fi card

- Refresh slice in WifiTracker.onConnectedChanged
- Only expose notifySliceChange to child in SliceBackgroundWorker

Fixes: 123270015
Test: make RunSettingsRoboTests -j ROBOTEST_FILTER=com.android.settings.wifi.slice
Change-Id: Id5540ebae2746e58e14924665c5e62bf437ebcf0

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

@@ -59,10 +59,6 @@ public abstract class SliceBackgroundWorker<E> implements Closeable {
         mUri = uri;
     }
 
-    protected Uri getUri() {
-        return mUri;
-    }
-
     /**
      * Returns the singleton instance of the {@link SliceBackgroundWorker} for specified {@link Uri}
      * if exists
@@ -148,7 +144,14 @@ public abstract class SliceBackgroundWorker<E> implements Closeable {
 
         if (needNotify) {
             mCachedResults = results;
-            mContext.getContentResolver().notifyChange(mUri, null);
+            notifySliceChange();
         }
     }
-}
+
+    /**
+     * Notify that data was updated and attempt to sync changes to the Slice.
+     */
+    protected void notifySliceChange() {
+        mContext.getContentResolver().notifyChange(mUri, null);
+    }
+}