AutoAnswer: add EditText preference

- code cleanup

Change-Id: Ic15b71f1037424a463b0b52c260c24745cb14b00
diff --git a/HelloWorld/CoinCircleVideoSubscriber.h b/HelloWorld/CoinCircleVideoSubscriber.h
index fb82a7f..9d38c6e 100644
--- a/HelloWorld/CoinCircleVideoSubscriber.h
+++ b/HelloWorld/CoinCircleVideoSubscriber.h
@@ -45,7 +45,7 @@
 
 private:
     // Observer pattern
-    Observable<AVFrame*>* observable_ = nullptr;
+    Observable<AVFrame*>* observable_{};
 
     // Data
     std::string path_;