add APK build time benchmarks (#35481)

dev/devicelab/bin/tasks/build_benchmark.dart

@@ -0,0 +1,12 @@
+// 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 'dart:async';
+
+import 'package:flutter_devicelab/framework/framework.dart';
+import 'package:flutter_devicelab/tasks/build_benchmarks.dart';
+
+Future<void> main() async {
+  await task(createBuildbenchmarkTask());
+}

dev/devicelab/lib/tasks/build_benchmarks.dart

@@ -0,0 +1,72 @@
+// Copyright 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:io';
+
+import 'package:flutter_devicelab/framework/framework.dart';
+import 'package:flutter_devicelab/framework/utils.dart';
+import 'package:path/path.dart' as path;
+
+final Directory helloWorldDir = dir(path.join(flutterDirectory.path, 'examples', 'hello_world'));
+
+/// Creates a device lab build benchmark.
+TaskFunction createBuildbenchmarkTask() {
+  return () async {
+    return inDirectory<TaskResult>(helloWorldDir, () async {
+      final Stopwatch stopwatch = Stopwatch()
+        ..start();
+      final Process initialBuild = await startProcess(
+        path.join(flutterDirectory.path, 'bin', 'flutter'),
+        <String>['build', 'apk', '--debug'],
+        environment: null,
+      );
+      int exitCode = await initialBuild.exitCode;
+      if (exitCode != 0) {
+        return TaskResult.failure('Failed to build debug APK');
+      }
+      final int initialBuildMilliseconds = stopwatch.elapsedMilliseconds;
+      stopwatch
+        ..reset()
+        ..start();
+      final Process secondBuild = await startProcess(
+        path.join(flutterDirectory.path, 'bin', 'flutter'),
+        <String>['build', 'apk', '--debug'],
+        environment: null,
+      );
+      exitCode = await secondBuild.exitCode;
+      if (exitCode != 0) {
+        return TaskResult.failure('Failed to build debug APK');
+      }
+      final int secondBuildMilliseconds = stopwatch.elapsedMilliseconds;
+      final Process newBuildConfig = await startProcess(
+        path.join(flutterDirectory.path, 'bin', 'flutter'),
+        <String>['build', 'apk', '--profile'],
+        environment: null,
+      );
+      exitCode = await newBuildConfig.exitCode;
+      if (exitCode != 0) {
+        return TaskResult.failure('Failed to build profile APK');
+      }
+      stopwatch
+        ..reset()
+        ..start();
+      final Process thirdBuild = await startProcess(
+        path.join(flutterDirectory.path, 'bin', 'flutter'),
+        <String>['build', 'apk', '--debug'],
+        environment: null,
+      );
+      exitCode = await thirdBuild.exitCode;
+      if (exitCode != 0) {
+        return TaskResult.failure('Failed to build debug APK');
+      }
+      final int thirdBuildMilliseconds = stopwatch.elapsedMilliseconds;
+      stopwatch.stop();
+      final Map<String, double> allResults = <String, double>{};
+      allResults['first_build_debug_millis'] = initialBuildMilliseconds.toDouble();
+      allResults['second_build_debug_millis'] = secondBuildMilliseconds.toDouble();
+      allResults['after_config_change_build_debug_millis'] = thirdBuildMilliseconds.toDouble();
+      return TaskResult.success(allResults, benchmarkScoreKeys: allResults.keys.toList());
+    });
+  };
+}

dev/devicelab/manifest.yaml

@@ -358,6 +358,13 @@ tasks:
     required_agent_capabilities: ["linux/android"]
     flaky: true
 
+  build_benchmark:
+    description: >
+      Measures APK build performance across config changes.
+    stage: devicelab
+    required_agent_capabilities: ["linux/android"]
+    flaky: true
+
   # iOS on-device tests
 
   flavors_test_ios: