Added license headers for M3 demo app (#1328)

* Added header for all files

Co-authored-by: Qun Cheng <quncheng@google.com>

material_3_demo/lib/color_palettes_screen.dart

@@ -1,3 +1,7 @@
+// Copyright 2021 The Flutter team. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
 import 'package:flutter/material.dart';
 
 const Widget divider = SizedBox(height: 10);

material_3_demo/lib/component_screen.dart

@@ -1,3 +1,7 @@
+// Copyright 2021 The Flutter team. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
 import 'package:flutter/material.dart';
 
 class ComponentScreen extends StatelessWidget {

material_3_demo/lib/elevation_screen.dart

@@ -1,3 +1,7 @@
+// Copyright 2021 The Flutter team. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
 import 'package:flutter/material.dart';
 
 class ElevationScreen extends StatelessWidget {

material_3_demo/lib/main.dart

@@ -1,3 +1,7 @@
+// Copyright 2021 The Flutter team. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
 import 'package:flutter/material.dart';
 
 import 'color_palettes_screen.dart';

material_3_demo/lib/typography_screen.dart

@@ -1,3 +1,7 @@
+// Copyright 2021 The Flutter team. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
 import 'package:flutter/material.dart';
 
 class TypographyScreen extends StatelessWidget {

material_3_demo/test/color_screen_test.dart

@@ -1,3 +1,7 @@
+// Copyright 2021 The Flutter team. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
 // ignore_for_file: avoid_types_on_closure_parameters
 import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
@@ -29,7 +33,7 @@ void main() {
 
   testWidgets(
       'Color palettes screen shows correctly when color icon is clicked '
-      'on NavigationRail', (WidgetTester tester) async {
+      'on NavigationRail', (tester) async {
     widgetSetup(tester, 450); // NavigationRail shows only when width is >= 450.
     addTearDown(tester.binding.window.clearPhysicalSizeTestValue);
     await tester.pumpWidget(const Material3Demo());
@@ -46,8 +50,7 @@ void main() {
     expect(find.text("Dark Theme"), findsOneWidget);
   });
 
-  testWidgets('Color screen shows correct content',
-      (WidgetTester tester) async {
+  testWidgets('Color screen shows correct content', (tester) async {
     await tester.pumpWidget(MaterialApp(
       home: Scaffold(body: Row(children: const [ColorPalettesScreen()])),
     ));

material_3_demo/test/component_screen_test.dart

@@ -1,3 +1,7 @@
+// Copyright 2021 The Flutter team. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
 // ignore_for_file: avoid_types_on_closure_parameters
 import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
@@ -5,8 +9,7 @@ import 'package:material_3_demo/component_screen.dart';
 import 'package:material_3_demo/main.dart';
 
 void main() {
-  testWidgets('Default main page shows all M3 components',
-      (WidgetTester tester) async {
+  testWidgets('Default main page shows all M3 components', (tester) async {
     await tester.pumpWidget(const Material3Demo());
 
     // Elements on the app bar

material_3_demo/test/elevation_screen_test.dart

@@ -1,3 +1,7 @@
+// Copyright 2021 The Flutter team. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
 // ignore_for_file: avoid_types_on_closure_parameters
 import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
@@ -9,7 +13,7 @@ import 'component_screen_test.dart';
 void main() {
   testWidgets(
       'Surface Tones screen shows correctly when the corresponding icon is '
-      'selected on NavigationBar', (WidgetTester tester) async {
+      'selected on NavigationBar', (tester) async {
     widgetSetup(tester, 449);
     addTearDown(tester.binding.window.clearPhysicalSizeTestValue);
     await tester.pumpWidget(const Material3Demo());
@@ -27,7 +31,7 @@ void main() {
 
   testWidgets(
       'Surface Tones screen shows correctly when the corresponding icon is '
-      'selected on NavigationRail', (WidgetTester tester) async {
+      'selected on NavigationRail', (tester) async {
     widgetSetup(tester, 450); // NavigationRail shows only when width is >= 450.
     addTearDown(tester.binding.window.clearPhysicalSizeTestValue);
     await tester.pumpWidget(const Material3Demo());
@@ -42,8 +46,7 @@ void main() {
     expect(find.text("Surface Tint only"), findsOneWidget);
   });
 
-  testWidgets('Surface Tones screen shows correct content',
-      (WidgetTester tester) async {
+  testWidgets('Surface Tones screen shows correct content', (tester) async {
     await tester.pumpWidget(MaterialApp(
       home: Scaffold(body: Row(children: const [ElevationScreen()])),
     ));

material_3_demo/test/typography_screen_test.dart

@@ -1,3 +1,7 @@
+// Copyright 2021 The Flutter team. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
 // ignore_for_file: avoid_types_on_closure_parameters
 import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
@@ -9,7 +13,7 @@ import 'component_screen_test.dart';
 void main() {
   testWidgets(
       'Typography screen shows correctly when the corresponding icon is '
-      'selected on NavigationBar', (WidgetTester tester) async {
+      'selected on NavigationBar', (tester) async {
     widgetSetup(tester, 449);
     addTearDown(tester.binding.window.clearPhysicalSizeTestValue);
     await tester.pumpWidget(const Material3Demo());
@@ -27,7 +31,7 @@ void main() {
 
   testWidgets(
       'Typography screen shows correctly when the corresponding icon is '
-      'selected on NavigationRail', (WidgetTester tester) async {
+      'selected on NavigationRail', (tester) async {
     widgetSetup(tester, 450); // NavigationRail shows only when width is >= 450.
     addTearDown(tester.binding.window.clearPhysicalSizeTestValue);
     await tester.pumpWidget(const Material3Demo());
@@ -42,8 +46,7 @@ void main() {
     expect(find.text("Display Large"), findsOneWidget);
   });
 
-  testWidgets('Typography screen shows correct content',
-      (WidgetTester tester) async {
+  testWidgets('Typography screen shows correct content', (tester) async {
     await tester.pumpWidget(MaterialApp(
       home: Scaffold(body: Row(children: const [TypographyScreen()])),
     ));