Add flutter_web samples (#75)

web/slide_puzzle/lib/src/theme_plaster.dart

@@ -0,0 +1,76 @@
+// Copyright 2019 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'app_state.dart';
+import 'flutter.dart';
+import 'shared_theme.dart';
+
+const _yellowIsh = Color.fromARGB(255, 248, 244, 233);
+const _chocolate = Color.fromARGB(255, 66, 66, 68);
+const _orangeIsh = Color.fromARGB(255, 224, 107, 83);
+
+class ThemePlaster extends SharedTheme {
+  @override
+  String get name => 'Plaster';
+
+  ThemePlaster(AppState baseTheme) : super(baseTheme);
+
+  @override
+  Color get puzzleThemeBackground => _chocolate;
+
+  @override
+  Color get puzzleBackgroundColor => _yellowIsh;
+
+  @override
+  Color get puzzleAccentColor => _orangeIsh;
+
+  @override
+  RoundedRectangleBorder get puzzleBorder => RoundedRectangleBorder(
+        side: const BorderSide(
+          color: Color.fromARGB(255, 103, 103, 105),
+          width: 8,
+        ),
+        borderRadius: BorderRadius.all(
+          Radius.circular(small ? 10 : 18),
+        ),
+      );
+
+  @override
+  Widget tileButton(int i) {
+    final correctColumn = i % puzzle.width;
+    final correctRow = i ~/ puzzle.width;
+
+    final primary = (correctColumn + correctRow).isEven;
+
+    if (i == puzzle.tileCount) {
+      assert(puzzle.solved);
+      return Center(
+        child: Icon(
+          Icons.thumb_up,
+          size: small ? 50 : 72,
+          color: _orangeIsh,
+        ),
+      );
+    }
+
+    final content = Text(
+      (i + 1).toString(),
+      style: TextStyle(
+        color: primary ? _yellowIsh : _chocolate,
+        fontFamily: 'Plaster',
+        fontSize: small ? 40 : 77,
+      ),
+    );
+
+    return createButton(
+      i,
+      content,
+      color: primary ? _orangeIsh : _yellowIsh,
+      shape: RoundedRectangleBorder(
+        side: BorderSide(color: primary ? _chocolate : _orangeIsh, width: 5),
+        borderRadius: BorderRadius.circular(5),
+      ),
+    );
+  }
+}