anchor.diff:    }
   
     void _sendMessage({String text}) {
  -    ChatMessage message = new ChatMessage(
  -      text: text,
  -      animationController: new AnimationController(
  -        duration: new Duration(milliseconds: 700),
  -        vsync: this,
  -      ),
  -    );
  -    setState(() {
  -      _messages.insert(0, message);
  +    reference.push().set({
  +      'text': text,
  +      'senderName': googleSignIn.currentUser.displayName,
  +      'senderPhotoUrl': googleSignIn.currentUser.photoUrl
       });
  -    message.animationController.forward();
       analytics.logEvent(name: 'send_message');
  -  }
  -
  -  void dispose() {
  -    for (ChatMessage message in _messages)
  -      message.animationController.dispose();
  -    super.dispose();
     }
   
     Widget _buildTextComposer() {
  
positive.code: import 'dart:async';
  import 'package:firebase_analytics/firebase_analytics.dart';
  import 'package:firebase_auth/firebase_auth.dart';
  
  final googleSignIn = new GoogleSignIn();
  final analytics = new FirebaseAnalytics();
  
negative.code:   }
  }
  
  @override
  class ChatMessage extends StatelessWidget {
  
    ChatMessage({this.snapshot, this.animation});
    final DataSnapshot snapshot;
    final Animation animation;
  
    @override
    Widget build(BuildContext context) {
      return new SizeTransition(
        sizeFactor: new CurvedAnimation(
          parent: animation, curve: Curves.easeOut
        ),
        axisAlignment: 0.0,
        child: new Container(
  