Re-enable chrome dev mode tests (#43691)

dev/devicelab/lib/tasks/web_dev_mode_tests.dart

@@ -9,30 +9,24 @@ import 'dart:io';
 import 'package:path/path.dart' as path;
 
 import '../framework/framework.dart';
-import '../framework/running_processes.dart';
 import '../framework/utils.dart';
 
 final Directory _editedFlutterGalleryDir = dir(path.join(Directory.systemTemp.path, 'edited_flutter_gallery'));
 final Directory flutterGalleryDir = dir(path.join(flutterDirectory.path, 'examples/flutter_gallery'));
 
+const String kInitialStartupTime = 'InitialStartupTime';
+const String kFirstRestartTime = 'FistRestartTime';
+const String kFirstRecompileTime  = 'FirstRecompileTime';
+const String kSecondStartupTime = 'SecondStartupTime';
+const String kSecondRestartTime = 'SecondRestartTime';
+
 TaskFunction createWebDevModeTest() {
   return () async {
     final List<String> options = <String>[
-      '--hot', '-d', 'chrome', '--verbose', '--resident', '--target=lib/main.dart',
+      '--hot', '-d', 'web-server', '--verbose', '--resident', '--target=lib/main.dart',
     ];
     int hotRestartCount = 0;
-    String chromeProcessName;
-    if (Platform.isMacOS) {
-      chromeProcessName = 'Chrome';
-    } else if (Platform.isLinux) {
-      chromeProcessName = 'chrome';
-    } else if (Platform.isWindows) {
-      chromeProcessName = 'chrome.exe';
-    }
-    final Set<String> beforeChromeProcesses = await getRunningProcesses(processName: chromeProcessName)
-      .map((RunningProcessInfo info) => info.pid)
-      .toSet();
-    try {
+    final Map<String, int> measurements = <String, int>{};
     await inDirectory<void>(flutterDirectory, () async {
       rmTree(_editedFlutterGalleryDir);
       mkdirs(_editedFlutterGalleryDir);
@@ -57,15 +51,23 @@ TaskFunction createWebDevModeTest() {
 
           final Completer<void> stdoutDone = Completer<void>();
           final Completer<void> stderrDone = Completer<void>();
+          final Stopwatch sw = Stopwatch()..start();
           process.stdout
               .transform<String>(utf8.decoder)
               .transform<String>(const LineSplitter())
               .listen((String line) {
             if (line.contains('To hot restart')) {
+              // measure clean start-up time.
+              sw.stop();
+              measurements[kInitialStartupTime] = sw.elapsedMilliseconds;
+              sw
+                ..reset()
+                ..start();
               process.stdin.write('R');
             }
-              if (line.contains('Restarted')) {
+            if (line.contains('Recompile complete')) {
               if (hotRestartCount == 0) {
+                measurements[kFirstRestartTime] = sw.elapsedMilliseconds;
                 // Update the file and reload again.
                 final File appDartSource = file(path.join(
                     _editedFlutterGalleryDir.path, 'lib/gallery/app.dart',
@@ -75,9 +77,13 @@ TaskFunction createWebDevModeTest() {
                         "'Flutter Gallery'", "'Updated Flutter Gallery'",
                     )
                 );
+                sw
+                  ..reset()
+                  ..start();
                 process.stdin.writeln('R');
                 ++hotRestartCount;
               } else {
+                measurements[kFirstRecompileTime] = sw.elapsedMilliseconds;
                 // Quit after second hot restart.
                 process.stdin.writeln('q');
               }
@@ -106,6 +112,8 @@ TaskFunction createWebDevModeTest() {
         // Start `flutter run` again to make sure it loads from the previous
         // state. dev compilers loads up from previously compiled JavaScript.
         {
+
+          final Stopwatch sw = Stopwatch()..start();
           final Process process = await startProcess(
               path.join(flutterDirectory.path, 'bin', 'flutter'),
               flutterCommandArgs('run', options),
@@ -119,10 +127,16 @@ TaskFunction createWebDevModeTest() {
               .transform<String>(utf8.decoder)
               .transform<String>(const LineSplitter())
               .listen((String line) {
+
             if (line.contains('To hot restart')) {
+              measurements[kSecondStartupTime] = sw.elapsedMilliseconds;
+              sw
+                ..reset()
+                ..start();
               process.stdin.write('R');
             }
-              if (line.contains('Restarted')) {
+            if (line.contains('Recompile complete')) {
+               measurements[kSecondRestartTime] = sw.elapsedMilliseconds;
               process.stdin.writeln('q');
             }
             print('stdout: $line');
@@ -146,18 +160,15 @@ TaskFunction createWebDevModeTest() {
         }
       });
     });
-    } finally {
-      final Set<String> afterChromeProcesses = await getRunningProcesses(processName: chromeProcessName)
-        .map((RunningProcessInfo info) => info.pid)
-        .toSet();
-      final Set<String> newProcesses = afterChromeProcesses.difference(beforeChromeProcesses);
-      for (String processId in newProcesses) {
-        await killProcess(processId);
-      }
-    }
     if (hotRestartCount != 1) {
       return TaskResult.failure(null);
     }
-    return TaskResult.success(null);
+    return TaskResult.success(measurements, benchmarkScoreKeys: <String>[
+      kInitialStartupTime,
+      kFirstRestartTime,
+      kFirstRecompileTime,
+      kSecondStartupTime,
+      kSecondRestartTime,
+    ]);
   };
 }

dev/devicelab/manifest.yaml

@@ -126,13 +126,12 @@ tasks:
     stage: devicelab_win
     required_agent_capabilities: ["windows/android"]
 
-  # TODO(jonahwilliams): re-enable with https://github.com/flutter/flutter/issues/39597
-  # windows_chrome_dev_mode:
-  #   description: >
-  #     Run flutter web on the devicelab and hot restart.
-  #   stage: devicelab_win
-  #   required_agent_capabilities: ["windows/android"]
-  #   flaky: true
+  windows_chrome_dev_mode:
+    description: >
+      Run flutter web on the devicelab and hot restart.
+    stage: devicelab_win
+    required_agent_capabilities: ["windows/android"]
+    flaky: true
 
   # Android on-device tests
 
@@ -346,13 +345,12 @@ tasks:
     stage: devicelab
     required_agent_capabilities: ["linux/android"]
 
-  # TODO(jonahwilliams): re-enable with https://github.com/flutter/flutter/issues/39597
-  # linux_chrome_dev_mode:
-  #   description: >
-  #     Run flutter web on the devicelab and hot restart.
-  #   stage: devicelab
-  #   required_agent_capabilities: ["linux/android"]
-  #   flaky: true
+  linux_chrome_dev_mode:
+    description: >
+      Run flutter web on the devicelab and hot restart.
+    stage: devicelab
+    required_agent_capabilities: ["linux/android"]
+    flaky: true
 
   web_size__compile_test:
     description: >
@@ -519,12 +517,12 @@ tasks:
     stage: devicelab_ios
     required_agent_capabilities: ["mac/ios"]
 
-  # macos_chrome_dev_mode:
-  #   description: >
-  #     Run flutter web on the devicelab and hot restart.
-  #   stage: devicelab_ios
-  #   required_agent_capabilities: ["mac/ios"]
-  #   flaky: true # marked as flaky while infra is under heavy development
+  macos_chrome_dev_mode:
+    description: >
+      Run flutter web on the devicelab and hot restart.
+    stage: devicelab_ios
+    required_agent_capabilities: ["mac/ios"]
+    flaky: true # marked as flaky while infra is under heavy development
 
   build_benchmark_ios:
     description: >