[web] onTextScaleFactorChanged not firing? #178271

import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      home: const MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({super.key, required this.title});

  final String title;

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  double _textScaleFactor = PlatformDispatcher.instance.textScaleFactor;

  @override
  void initState() {
    super.initState();
    // This is not firing as browser settings are updated!
    PlatformDispatcher.instance.onTextScaleFactorChanged = (() {
      setState(() {
        _textScaleFactor = PlatformDispatcher.instance.textScaleFactor;
      });
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        backgroundColor: Theme.of(context).colorScheme.inversePrimary,
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: .center,
          children: [
            const Text('The current textScaleFactor is:'),
            Text(
              '$_textScaleFactor',
              style: Theme.of(context).textTheme.headlineMedium,
            ),
          ],
        ),
      ),
    );
  }
}