Add performance tests for the new gallery (#55181)

dev/devicelab/bin/tasks/new_gallery__transition_perf.dart

@@ -0,0 +1,25 @@
+// Copyright 2014 The Flutter 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 'dart:io';
+
+import 'package:flutter_devicelab/framework/utils.dart';
+import 'package:flutter_devicelab/tasks/new_gallery.dart';
+import 'package:flutter_devicelab/framework/adb.dart';
+import 'package:flutter_devicelab/framework/framework.dart';
+import 'package:path/path.dart' as path;
+
+Future<void> main() async {
+  deviceOperatingSystem = DeviceOperatingSystem.android;
+
+  final Directory galleryParentDir = Directory.systemTemp.createTempSync('new_gallery_test');
+  final Directory galleryDir = Directory(path.join(galleryParentDir.path, 'gallery'));
+
+  try {
+    await task(NewGalleryPerfTest(galleryDir).run);
+  } finally {
+    rmTree(galleryParentDir);
+  }
+}

dev/devicelab/lib/framework/utils.dart

@@ -501,6 +501,22 @@ String jsonEncode(dynamic data) {
   return const JsonEncoder.withIndent('  ').convert(data) + '\n';
 }
 
+Future<void> getNewGallery(String revision, Directory galleryDir) async {
+  section('Get New Flutter Gallery!');
+
+  if (exists(galleryDir)) {
+    galleryDir.deleteSync(recursive: true);
+  }
+
+  await inDirectory<void>(galleryDir.parent, () async {
+    await exec('git', <String>['clone', 'https://github.com/flutter/gallery.git']);
+  });
+
+  await inDirectory<void>(galleryDir, () async {
+    await exec('git', <String>['checkout', revision]);
+  });
+}
+
 void checkNotNull(Object o1,
     [Object o2 = 1,
     Object o3 = 1,

dev/devicelab/lib/tasks/new_gallery.dart

@@ -0,0 +1,27 @@
+// Copyright 2014 The Flutter 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 'dart:io';
+
+import 'package:flutter_devicelab/tasks/perf_tests.dart';
+
+
+import '../framework/framework.dart';
+import '../framework/utils.dart';
+
+class NewGalleryPerfTest extends PerfTest {
+  NewGalleryPerfTest(this.galleryDir) : super(galleryDir.path, 'test_driver/transitions_perf.dart', 'transitions');
+
+  @override
+  Future<TaskResult> run() async {
+    // Manually roll the new gallery version for now. If the new gallery repo
+    // turns out to be updated frequently in the future, we can set up an auto
+    // roller to update this version.
+    await getNewGallery('59489e5571ddf554fc62ef52e9b16f1fed291026', galleryDir);
+    return await super.run();
+  }
+
+  final Directory galleryDir;
+}

dev/devicelab/manifest.yaml

@@ -749,6 +749,12 @@ tasks:
     stage: devicelab
     required_agent_capabilities: ["linux/android"]
 
+  new_gallery__transition_perf:
+    description: >
+      Measures the performance of screen transitions in the new Flutter Gallery on Android.
+    stage: devicelab
+    required_agent_capabilities: ["mac/android"]
+
   fast_scroll_large_images__memory:
     description: >
       Measures memory usage for scrolling through a list of large images.