add tasks for Windows bots in device lab (#8827)

dev/devicelab/bin/tasks/flutter_gallery_win__build.dart

+// Copyright (c) 2017 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 'dart:async';
+
+import 'flutter_gallery__build.dart' as flutter_gallery_build;
+
+Future<Null> main() async {
+  await flutter_gallery_build.main();
+}

dev/devicelab/bin/tasks/hot_mode_dev_cycle_win__benchmark.dart

+// Copyright (c) 2017 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 'hot_mode_dev_cycle__benchmark.dart' as hot_mode_dev_cycle_benchmark;
+
+void main() {
+  hot_mode_dev_cycle_benchmark.main();
+}

dev/devicelab/manifest.yaml

@@ -178,3 +178,18 @@ tasks:
       Runs benchmarks from dev/benchmarks/microbenchmarks on iOS.
     stage: devicelab_ios
     required_agent_capabilities: ["has-ios-device"]
+
+  # Tests running on Windows host
+
+  flutter_gallery_win__build:
+    description: >
+      Collects various performance metrics from AOT builds of the Flutter
+      Gallery on Windows.
+    stage: devicelab_win
+    required_agent_capabilities: ["windows"]
+
+  hot_mode_dev_cycle_win__benchmark:
+    description: >
+      Measures the performance of Dart VM hot patching feature on Windows.
+    stage: devicelab_win
+    required_agent_capabilities: ["windows"]