Repository: flutter
Issue: CupertinoBar color does not update with brightness, for dark mode.
Labels: framework,f: cupertino,has reproducible steps,found in release: 3.3,found in release: 3.7,team-design,triaged-design

<!-- Thank you for using Flutter!

     If you are looking for support, please check out our documentation
     or consider asking a question on Stack Overflow:
      * https://flutter.dev/
      * https://api.flutter.dev/
      * https://stackoverflow.com/questions/tagged/flutter?sort=frequent

     If you have found a bug or if our documentation doesn't have an answer
     to what you're looking for, then fill our the template below. Please read
     our guide to filing a bug first: https://flutter.dev/docs/resources/bug-reports
-->

## Steps to Reproduce
<!-- You must include full steps to reproduce so that we can reproduce the problem. -->

1. Run `flutter create bug`.
2. Update the main.dart as follows: 

```
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        cupertinoOverrideTheme:
            const CupertinoThemeData(brightness: Brightness.dark),
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Flutter Demo Home'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);
  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0;

  void _incrementCounter() {
    setState(() {
      _counter++;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: Text(widget.title),
        ),
        body: Center(
          child: Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: <Widget>[
              Text(
                'You have pushed the button this many times:',
              ),
              Text(
                '$_counter',
                style: Theme.of(context).textTheme.display1,
              ),
            ],
          ),
        ),
        floatingActionButton: FloatingActionButton(
          onPressed: _incrementCounter,
          tooltip: 'Increment',
          child: Icon(Icons.add),
        ),
        bottomNavigationBar: CupertinoTabBar(
          items: [
            BottomNavigationBarItem(
              icon: Icon(Icons.ac_unit),
              title: Text('AC'),
            ),
            BottomNavigationBarItem(
              icon: Icon(Icons.access_alarm),
              title: Text('Alarm'),
            ),
          ],
        )
        );
  }
}
```
**Expected results:** <!-- what did you want to see? -->

 If brightness is Light, the status bar icons should be black or viceversa. If brightness is Black, app bar should be black.
```
cupertinoOverrideTheme:
            const CupertinoThemeData(brightness: Brightness.dark), 
```
**Actual results:** <!-- what did you see? -->
Only the CupertinoTabBar is updating if overriding, if not overriding but dark theme is on it works too but no the app bar.

![image](https://user-images.githubusercontent.com/21696326/75829901-67ae6900-5d7d-11ea-872c-5b1ad303238a.png)

<details>
  <summary>Logs</summary>

<!-- Finally, paste the output of running `flutter doctor -v` here. -->
Flutter Doctor
```
[✓] Flutter (Channel stable, v1.12.13+hotfix.8, on Mac OS X 10.15.3 19D76, locale en-CO)
    • Flutter version 1.12.13+hotfix.8 at /Users/nicolas.villamizar/flutter
    • Framework revision 0b8abb4724 (3 weeks ago), 2020-02-11 11:44:36 -0800
    • Engine revision e1e6ced81d
    • Dart version 2.7.0

 
[✓] Android toolchain - develop for Android devices (Android SDK version 29.0.3)
    • Android SDK at /Users/nicolas.villamizar/Library/Android/sdk
    • Android NDK location not configured (optional; useful for native profiling support)
    • Platform android-29, build-tools 29.0.3
    • Java binary at: /Applications/Android Studio.app/Contents/jre/jdk/Contents/Home/bin/java
    • Java version OpenJDK Runtime Environment (build 1.8.0_212-release-1586-b4-5784211)
    • All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS (Xcode 11.3.1)
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Xcode 11.3.1, Build version 11C504
    • CocoaPods version 1.8.4

[✓] Android Studio (version 3.6)
    • Android Studio at /Applications/Android Studio.app/Contents
    • Flutter plugin version 43.0.2
    • Dart plugin version 192.7761
    • Java version OpenJDK Runtime Environment (build 1.8.0_212-release-1586-b4-5784211)

[✓] VS Code (version 1.42.1)
    • VS Code at /Applications/Visual Studio Code.app/Contents
    • Flutter extension version 3.8.1

[✓] Connected device (1 available)
    • iPhone 11 • A27B9117-A941-4F9F-8177-60DEA19279F7 • ios • com.apple.CoreSimulator.SimRuntime.iOS-13-3 (simulator)

• No issues found!
```

</details>