improve KeepAliveService

src/main/java/org/thoughtcrime/securesms/connect/KeepAliveService.java

@@ -77,11 +77,17 @@ public class KeepAliveService extends Service {
         return null;
     }
 
+    @Override
     public void onDestroy() {
         Log.i("DeltaChat", "*** KeepAliveService.onDestroy()");
         // the service will be restarted due to START_STICKY automatically, there's nothing more to do.
     }
 
+    @Override
+    public void onTimeout(int startId, int fgsType) {
+        stopSelf();
+    }
+
     static public KeepAliveService getInstance()
     {
         return s_this; // may be null