Add window setup to provider_counter (#1046)

provider_counter/lib/main.dart

@@ -2,10 +2,15 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'dart:io';
+
+import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:provider/provider.dart';
+import 'package:window_size/window_size.dart';
 
 void main() {
+  setupWindow();
   runApp(
     // Provide the model to all widgets within the app. We're using
     // ChangeNotifierProvider because that's a simple way to rebuild
@@ -23,6 +28,25 @@ void main() {
   );
 }
 
+const double windowWidth = 360;
+const double windowHeight = 640;
+
+void setupWindow() {
+  if (!kIsWeb && (Platform.isWindows || Platform.isLinux || Platform.isMacOS)) {
+    WidgetsFlutterBinding.ensureInitialized();
+    setWindowTitle('Provider Counter');
+    setWindowMinSize(const Size(windowWidth, windowHeight));
+    setWindowMaxSize(const Size(windowWidth, windowHeight));
+    getCurrentScreen().then((screen) {
+      setWindowFrame(Rect.fromCenter(
+        center: screen!.frame.center,
+        width: windowWidth,
+        height: windowHeight,
+      ));
+    });
+  }
+}
+
 /// Simplest possible model, with just one field.
 ///
 /// [ChangeNotifier] is a class in `flutter:foundation`. [Counter] does