Add startup test for Platform View example (#17645)

dev/devicelab/bin/tasks/platform_view__start_up.dart

+// Copyright 2018 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/tasks/perf_tests.dart';
+import 'package:flutter_devicelab/framework/adb.dart';
+import 'package:flutter_devicelab/framework/framework.dart';
+
+Future<Null> main() async {
+  deviceOperatingSystem = DeviceOperatingSystem.android;
+  await task(createPlatformViewStartupTest());
+}

dev/devicelab/bin/tasks/platform_view_ios__start_up.dart

+// Copyright 2018 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 'dart:io';
+
+import 'package:flutter_devicelab/framework/utils.dart';
+import 'package:flutter_devicelab/tasks/perf_tests.dart';
+import 'package:flutter_devicelab/framework/adb.dart';
+import 'package:flutter_devicelab/framework/framework.dart';
+
+Future<Null> main() async {
+  deviceOperatingSystem = DeviceOperatingSystem.ios;
+  await task(() async {
+    final Directory iosDirectory = dir(
+      '${flutterDirectory.path}/examples/platform_view/ios',
+    );
+    await inDirectory(iosDirectory, () async {
+      await exec('pod', <String>['install']);
+    });
+
+    final TaskFunction taskFunction = createPlatformViewStartupTest();
+    return await taskFunction();
+  });
+}

dev/devicelab/lib/tasks/perf_tests.dart

@@ -77,6 +77,13 @@ TaskFunction createFlutterViewStartupTest() {
   ).run;
 }
 
+TaskFunction createPlatformViewStartupTest() {
+  return new StartupTest(
+    '${flutterDirectory.path}/examples/platform_view',
+    reportMetrics: false,
+  ).run;
+}
+
 TaskFunction createBasicMaterialCompileTest() {
   return () async {
     const String sampleAppName = 'sample_flutter_app';

dev/devicelab/manifest.yaml

@@ -136,6 +136,12 @@ tasks:
     stage: devicelab
     required_agent_capabilities: ["mac/android"]
 
+  platform_view__start_up:
+    description: >
+      Verifies that Platform View can be used from an Android project.
+    stage: devicelab
+    required_agent_capabilities: ["mac/android"]
+
   complex_layout__start_up:
     description: >
       Measures the startup time of the Complex Layout sample app on Android.
@@ -289,6 +295,12 @@ tasks:
     stage: devicelab_ios
     required_agent_capabilities: ["mac/ios"]
 
+  platform_view_ios__start_up:
+    description: >
+      Verifies that Platform View can be used from an iOS project.
+    stage: devicelab_ios
+    required_agent_capabilities: ["mac/ios"]
+
   complex_layout_scroll_perf_ios__timeline_summary:
     description: >
       Measures the runtime performance of the Complex Layout sample app on