VM Service isolate listing

runtime/bin/vmservice/vmservice.dart

Index: runtime/bin/vmservice/vmservice.dart
diff --git a/runtime/bin/vmservice/vmservice.dart b/runtime/bin/vmservice/vmservice.dart
index e074e9a4d4b6663c78fa2652a7c9f2ca5fbd48c4..f1f8995a7396b1d61ad395f97d9c59bdb89b30d4 100644
--- a/runtime/bin/vmservice/vmservice.dart
+++ b/runtime/bin/vmservice/vmservice.dart
@@ -6,16 +6,45 @@ library vmservice;
 
 import 'dart:async';
 import 'dart:json' as JSON;
+// TODO(11927): Factor 'dart:io' dependency into separate library.
 import 'dart:io';
 import 'dart:isolate';
 import 'dart:typed_data';
 import 'dart:utf' as UTF;
 
 
-void messageHandler(message, SendPort replyTo) {
-}
+class VmService {
+  static VmService _instance;
+  RunningIsolates runningIsolates = new RunningIsolates();
+
+  void controlMessageHandler(int code, SendPort sp) {
+    switch (code) {
+      case Constants.ISOLATE_STARTUP_MESSAGE_ID:
+        runningIsolates.isolateStartup(sp);
+      break;
+      case Constants.ISOLATE_SHUTDOWN_MESSAGE_ID:
+        runningIsolates.isolateShutdown(sp);
+      break;
+    }
+  }
 
+  void messageHandler(message, SendPort replyTo) {
+    if (message is List && message.length == 2) {
+      controlMessageHandler(message[0], message[1]);
+    }
+  }
 
-main() {
-  port.receive(messageHandler);
+  VmService._internal() {
+    port.receive(messageHandler);
+  }
+
+  factory VmService() {
+    if (VmService._instance == null) {
+      VmService._instance = new VmService._internal();
+    }
+    return _instance;
+  }
 }
+
+void sendServiceMessage(SendPort sp, ReceivePort rp, Object m)
+    native "SendServiceMessage";