title: get widget observer for WidgetsBindingObserver
body: <p>I'm trying to add WidgetsBindingObserver  accoidring to (<a href="https://medium.com/@phongyewtong/best-method-to-restart-reload-your-flutter-app-on-startup-2f787cecc6d6" rel="nofollow noreferrer">https://medium.com/@phongyewtong/best-method-to-restart-reload-your-flutter-app-on-startup-2f787cecc6d6</a>)</p>
  <pre><code>
  class MyApp extends StatefulWidget with WidgetsBindingObserver {
    @override
    _MyAppState createState() =&gt; _MyAppState();
  }
  
  class _MyAppState extends State&lt;MyApp&gt; {
    @override
    void initState() {
      super.initState();
      WidgetsBinding.instance.addObserver(this);   // The Error is right here
    }
  
    @override
    void dispose() {
      WidgetsBinding.instance.removeObserver(this);
  
      super.dispose();
    }
  
    @override
    Widget build(BuildContext context) {
      return MaterialHomeApp();
    }
  </code></pre>
  <p>The Erros says <code>The argument type '_MyAppState' can't be assigned to the parameter type 'WidgetsBindingObserver'.dartargument_type_not_assignable</code></p>