title: Flutter: Not able to show local notification when the app is in background
body: <blockquote>
  <p>EDIT: This issue is fixed on the latest flutter and firebase version.</p>
  </blockquote>
  <p>I'm listening to Firebase FCM <code>data</code> type messages and on receiving FCM messages, I intended to show a local notification from within the app.</p>
  <pre><code>_firebaseMessaging.configure(
        onMessage: (Map&lt;String, dynamic&gt; message) async {
          print('on message $message');
          LocalNotificationService.showNotoficationWithDefaultSound(&quot;onmessage&quot;);
        },
        onResume: (Map&lt;String, dynamic&gt; message) async {
          LocalNotificationService.showNotoficationWithDefaultSound(&quot;onresume&quot;);
          print('on resume $message');
        },
        onLaunch: (Map&lt;String, dynamic&gt; message) async {
          LocalNotificationService.showNotoficationWithDefaultSound(&quot;onlaunch&quot;);
          print('on launch $message');
        },
        onBackgroundMessage: myBackgroundMessageHandler,
      );
  
  
  /// Yes. This is a global function
  Future&lt;dynamic&gt; myBackgroundMessageHandler(Map&lt;String, dynamic&gt; message) {
    var androidPlatformChannelSpecifics = new AndroidNotificationDetails(
        'chanID_007', 'chanName_kk107', 'This is my channel');
    var iosPlatformChannelSpecifics = new IOSNotificationDetails();
    var platformChannelSpecifics = new NotificationDetails(
        androidPlatformChannelSpecifics, iosPlatformChannelSpecifics);
    FlutterLocalNotificationsPlugin flutterLocalNotificationsPlugin;
    var initializationSettingsAndroid =
        new AndroidInitializationSettings('@mipmap/ic_launcher');
    var initializationSettingsIos = new IOSInitializationSettings();
    var initializationSettings = new InitializationSettings(
        initializationSettingsAndroid, initializationSettingsIos);
    flutterLocalNotificationsPlugin = new FlutterLocalNotificationsPlugin();
    flutterLocalNotificationsPlugin.initialize(initializationSettings,
        onSelectNotification: onSelectNotification);
  
  
   await flutterLocalNotificationsPlugin.show(
    0, 'Tada!!', 'test', platformChannelSpecifics,
    payload: 'payload#7');
    print(&quot;background mssg&quot;);
  }
  </code></pre>
  <p>But showing the local notification with flutter_local_notification plugin throws an error</p>
  <p><code>Unhandled Exception: MissingPluginException(No implementation found for method initialize on channel dexterous.com/flutter/local_notifications)</code></p>
  <p>What am I missing here?</p>