Added a onRestrictBackgroundBlacklistChanged() callback.

When an UID is added / removed to the Data Saver blacklist, it's
necessary to notify internal components such as the Settings UI (which
was erroneously listening to UID rules changes instead).

BUG: 28743623
BUG: 28791717

Change-Id: I11c85e141dfe074ad390fd324309d2412bfbbd45

services/core/java/com/android/server/ConnectivityService.java

@@ -1445,6 +1445,14 @@ public class ConnectivityService extends IConnectivityManager.Stub
                         + whitelisted + ")");
             }
         }
+        @Override
+        public void onRestrictBackgroundBlacklistChanged(int uid, boolean blacklisted) {
+            if (LOGD_RULES) {
+                // caller is NPMS, since we only register with them
+                log("onRestrictBackgroundBlacklistChanged(uid=" + uid + ", blacklisted="
+                        + blacklisted + ")");
+            }
+        }
     };
 
     /**