diff --git a/dev/devicelab/lib/framework/running_processes.dart b/dev/devicelab/lib/framework/running_processes.dart
index 0efb77c4a4e..7ff6f8a6131 100644
--- a/dev/devicelab/lib/framework/running_processes.dart
+++ b/dev/devicelab/lib/framework/running_processes.dart
@@ -14,7 +14,7 @@ class RunningProcessInfo {
         assert(commandLine != null);
 
   final String commandLine;
-  final int pid;
+  final String pid;
   final DateTime creationDate;
 
   @override
@@ -47,7 +47,7 @@ class RunningProcessInfo {
   }
 }
 
-Future<bool> killProcess(int pid, {ProcessManager processManager}) async {
+Future<bool> killProcess(String pid, {ProcessManager processManager}) async {
   assert(pid != null, 'Must specify a pid to kill');
   processManager ??= const LocalProcessManager();
   ProcessResult result;
@@ -55,14 +55,14 @@ Future<bool> killProcess(int pid, {ProcessManager processManager}) async {
     result = await processManager.run(<String>[
       'taskkill.exe',
       '/pid',
-      pid.toString(),
+      pid,
       '/f',
     ]);
   } else {
     result = await processManager.run(<String>[
       'kill',
       '-9',
-      pid.toString(),
+      pid,
     ]);
   }
   return result.exitCode == 0;
@@ -163,7 +163,7 @@ Iterable<RunningProcessInfo> processPowershellOutput(String output) sync* {
       time = '${hours + 12}${time.substring(2)}';
     }
 
-    final int pid = int.parse(line.substring(0, processIdHeaderSize).trim());
+    final String pid = line.substring(0, processIdHeaderSize).trim();
     final DateTime creationDate = DateTime.parse('$year-$month-${day}T$time');
     final String commandLine = line.substring(commandLineHeaderStart).trim();
     yield RunningProcessInfo(pid, creationDate, commandLine);
@@ -254,7 +254,7 @@ Iterable<RunningProcessInfo> processPsOutput(
     final DateTime creationDate = DateTime.parse('$year-$month-${day}T$time');
     line = line.substring(24).trim();
     final int nextSpace = line.indexOf(' ');
-    final int pid = int.parse(line.substring(0, nextSpace));
+    final String pid = line.substring(0, nextSpace);
     final String commandLine = line.substring(nextSpace + 1);
     yield RunningProcessInfo(pid, creationDate, commandLine);
   }
diff --git a/dev/devicelab/lib/tasks/web_dev_mode_tests.dart b/dev/devicelab/lib/tasks/web_dev_mode_tests.dart
index af96e095bc4..78cf94eadea 100644
--- a/dev/devicelab/lib/tasks/web_dev_mode_tests.dart
+++ b/dev/devicelab/lib/tasks/web_dev_mode_tests.dart
@@ -9,6 +9,7 @@ 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'));
@@ -20,119 +21,140 @@ TaskFunction createWebDevModeTest() {
       '--hot', '-d', 'chrome', '--verbose', '--resident', '--target=lib/main.dart',
     ];
     int hotRestartCount = 0;
-    await inDirectory<void>(flutterDirectory, () async {
-      rmTree(_editedFlutterGalleryDir);
-      mkdirs(_editedFlutterGalleryDir);
-      recursiveCopy(flutterGalleryDir, _editedFlutterGalleryDir);
-      await inDirectory<void>(_editedFlutterGalleryDir, () async {
-        {
-          final Process packagesGet = await startProcess(
-              path.join(flutterDirectory.path, 'bin', 'flutter'),
-              <String>['packages', 'get'],
-              environment: <String, String>{
-                'FLUTTER_WEB': 'true',
-              },
-          );
-          await packagesGet.exitCode;
-          final Process process = await startProcess(
-              path.join(flutterDirectory.path, 'bin', 'flutter'),
-              flutterCommandArgs('run', options),
-              environment: <String, String>{
-                'FLUTTER_WEB': 'true',
-              },
-          );
+    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 {
+      await inDirectory<void>(flutterDirectory, () async {
+        rmTree(_editedFlutterGalleryDir);
+        mkdirs(_editedFlutterGalleryDir);
+        recursiveCopy(flutterGalleryDir, _editedFlutterGalleryDir);
+        await inDirectory<void>(_editedFlutterGalleryDir, () async {
+          {
+            final Process packagesGet = await startProcess(
+                path.join(flutterDirectory.path, 'bin', 'flutter'),
+                <String>['packages', 'get'],
+                environment: <String, String>{
+                  'FLUTTER_WEB': 'true',
+                },
+            );
+            await packagesGet.exitCode;
+            final Process process = await startProcess(
+                path.join(flutterDirectory.path, 'bin', 'flutter'),
+                flutterCommandArgs('run', options),
+                environment: <String, String>{
+                  'FLUTTER_WEB': 'true',
+                },
+            );
 
-          final Completer<void> stdoutDone = Completer<void>();
-          final Completer<void> stderrDone = Completer<void>();
-          process.stdout
-              .transform<String>(utf8.decoder)
-              .transform<String>(const LineSplitter())
-              .listen((String line) {
-            if (line.contains('To hot restart')) {
-              process.stdin.write('R');
-            }
-            if (line.contains('Restarted')) {
-              if (hotRestartCount == 0) {
-                // Update the file and reload again.
-                final File appDartSource = file(path.join(
-                    _editedFlutterGalleryDir.path, 'lib/gallery/app.dart',
-                ));
-                appDartSource.writeAsStringSync(
-                    appDartSource.readAsStringSync().replaceFirst(
-                        "'Flutter Gallery'", "'Updated Flutter Gallery'",
-                    )
-                );
-                process.stdin.writeln('R');
-                ++hotRestartCount;
-              } else {
-                // Quit after second hot restart.
+            final Completer<void> stdoutDone = Completer<void>();
+            final Completer<void> stderrDone = Completer<void>();
+            process.stdout
+                .transform<String>(utf8.decoder)
+                .transform<String>(const LineSplitter())
+                .listen((String line) {
+              if (line.contains('To hot restart')) {
+                process.stdin.write('R');
+              }
+              if (line.contains('Restarted')) {
+                if (hotRestartCount == 0) {
+                  // Update the file and reload again.
+                  final File appDartSource = file(path.join(
+                      _editedFlutterGalleryDir.path, 'lib/gallery/app.dart',
+                  ));
+                  appDartSource.writeAsStringSync(
+                      appDartSource.readAsStringSync().replaceFirst(
+                          "'Flutter Gallery'", "'Updated Flutter Gallery'",
+                      )
+                  );
+                  process.stdin.writeln('R');
+                  ++hotRestartCount;
+                } else {
+                  // Quit after second hot restart.
+                  process.stdin.writeln('q');
+                }
+              }
+              print('stdout: $line');
+            }, onDone: () {
+              stdoutDone.complete();
+            });
+            process.stderr
+                .transform<String>(utf8.decoder)
+                .transform<String>(const LineSplitter())
+                .listen((String line) {
+              print('stderr: $line');
+            }, onDone: () {
+              stderrDone.complete();
+            });
+
+            await Future.wait<void>(<Future<void>>[
+              stdoutDone.future,
+              stderrDone.future,
+            ]);
+            await process.exitCode;
+
+          }
+
+          // Start `flutter run` again to make sure it loads from the previous
+          // state. dev compilers loads up from previously compiled JavaScript.
+          {
+            final Process process = await startProcess(
+                path.join(flutterDirectory.path, 'bin', 'flutter'),
+                flutterCommandArgs('run', options),
+                environment: <String, String>{
+                  'FLUTTER_WEB': 'true',
+                },
+            );
+            final Completer<void> stdoutDone = Completer<void>();
+            final Completer<void> stderrDone = Completer<void>();
+            process.stdout
+                .transform<String>(utf8.decoder)
+                .transform<String>(const LineSplitter())
+                .listen((String line) {
+              if (line.contains('To hot restart')) {
+                process.stdin.write('R');
+              }
+              if (line.contains('Restarted')) {
                 process.stdin.writeln('q');
               }
-            }
-            print('stdout: $line');
-          }, onDone: () {
-            stdoutDone.complete();
-          });
-          process.stderr
-              .transform<String>(utf8.decoder)
-              .transform<String>(const LineSplitter())
-              .listen((String line) {
-            print('stderr: $line');
-          }, onDone: () {
-            stderrDone.complete();
-          });
+              print('stdout: $line');
+            }, onDone: () {
+              stdoutDone.complete();
+            });
+            process.stderr
+                .transform<String>(utf8.decoder)
+                .transform<String>(const LineSplitter())
+                .listen((String line) {
+              print('stderr: $line');
+            }, onDone: () {
+              stderrDone.complete();
+            });
 
-          await Future.wait<void>(<Future<void>>[
-            stdoutDone.future,
-            stderrDone.future,
-          ]);
-          await process.exitCode;
-
-        }
-
-        // Start `flutter run` again to make sure it loads from the previous
-        // state. dev compilers loads up from previously compiled JavaScript.
-        {
-          final Process process = await startProcess(
-              path.join(flutterDirectory.path, 'bin', 'flutter'),
-              flutterCommandArgs('run', options),
-              environment: <String, String>{
-                'FLUTTER_WEB': 'true',
-              },
-          );
-          final Completer<void> stdoutDone = Completer<void>();
-          final Completer<void> stderrDone = Completer<void>();
-          process.stdout
-              .transform<String>(utf8.decoder)
-              .transform<String>(const LineSplitter())
-              .listen((String line) {
-            if (line.contains('To hot restart')) {
-              process.stdin.write('R');
-            }
-            if (line.contains('Restarted')) {
-              process.stdin.writeln('q');
-            }
-            print('stdout: $line');
-          }, onDone: () {
-            stdoutDone.complete();
-          });
-          process.stderr
-              .transform<String>(utf8.decoder)
-              .transform<String>(const LineSplitter())
-              .listen((String line) {
-            print('stderr: $line');
-          }, onDone: () {
-            stderrDone.complete();
-          });
-
-          await Future.wait<void>(<Future<void>>[
-            stdoutDone.future,
-            stderrDone.future,
-          ]);
-          await process.exitCode;
-        }
+            await Future.wait<void>(<Future<void>>[
+              stdoutDone.future,
+              stderrDone.future,
+            ]);
+            await process.exitCode;
+          }
+        });
       });
-    });
+    } 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);
     }
diff --git a/dev/devicelab/test/running_processes_test.dart b/dev/devicelab/test/running_processes_test.dart
index 395ada4673f..5aa9f37878b 100644
--- a/dev/devicelab/test/running_processes_test.dart
+++ b/dev/devicelab/test/running_processes_test.dart
@@ -24,17 +24,17 @@ ProcessId CreationDate         CommandLine
         results,
         equals(<RunningProcessInfo>[
           RunningProcessInfo(
-            6552,
+            '6552',
             DateTime(2019, 7, 3, 17, 0, 27),
             r'"C:\tools\dart-sdk\bin\dart.exe" .\bin\agent.dart ci',
           ),
           RunningProcessInfo(
-            6553,
+            '6553',
             DateTime(2019, 7, 3, 22, 0, 27),
             r'"C:\tools\dart-sdk1\bin\dart.exe" .\bin\agent.dart ci',
           ),
           RunningProcessInfo(
-            6554,
+            '6554',
             DateTime(2019, 7, 3, 11, 0, 27),
             r'"C:\tools\dart-sdk2\bin\dart.exe" .\bin\agent.dart ci',
           ),
@@ -54,12 +54,12 @@ Sat Mar  9 20:13:00 2019        49 /usr/sbin/syslogd
         results,
         equals(<RunningProcessInfo>[
           RunningProcessInfo(
-            1,
+            '1',
             DateTime(2019, 3, 9, 20, 12, 47),
             '/sbin/launchd',
           ),
           RunningProcessInfo(
-            49,
+            '49',
             DateTime(2019, 3, 9, 20, 13, 00),
             '/usr/sbin/syslogd',
           ),