Add a VM page to the observatory.

runtime/vm/service/running_isolates.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of vmservice;
 
 class RunningIsolates implements MessageRouter {
   final Map<int, RunningIsolate> isolates = new Map<int, RunningIsolate>();
 
   RunningIsolates();
 
   void isolateStartup(int portId, SendPort sp, String name) {
     var ri = new RunningIsolate(portId, sp, name);
     isolates[portId] = ri;
   }
 
   void isolateShutdown(int portId, SendPort sp) {
     isolates.remove(portId);
   }
 
-  void _isolateCollectionRequest(Message message) {
-    var members = [];
-    var result = {};
-    isolates.forEach((portId, runningIsolate) {
-      members.add({
-          'type': '@Isolate',
-          'id': 'isolates/$portId',
-          'name': '$portId',
-      });
-    });
-    result['type'] = 'IsolateList';
-    result['id'] = 'isolates';
-    result['members'] = members;
-    message.setResponse(JSON.encode(result));
-  }
-
   Future<String> route(Message message) {
     if (message.path.length == 0) {
       message.setErrorResponse('No path.');
       return message.response;
     }
     if (message.path[0] != 'isolates') {
-      message.setErrorResponse('Path must begin with /isolates/.');
+      message.setErrorResponse('Path must begin with /isolates/');
       return message.response;
     }
-    if (message.path.length == 1) {
-      // Requesting list of running isolates.
-      _isolateCollectionRequest(message);
+    if (message.path.length < 2) {
+      message.setErrorResponse('An isolate id must be provided');
       return message.response;
     }
     var isolateId;
     try {
       isolateId = int.parse(message.path[1]);
     } catch (e) {
       message.setErrorResponse('Could not parse isolate id: $e');
       return message.response;
     }
     var isolate = isolates[isolateId];
     if (isolate == null) {
       message.setErrorResponse('Cannot find isolate id: $isolateId');
       return message.response;
     }
     // Consume '/isolates/isolateId'
     message.path.removeRange(0, 2);
     return isolate.route(message);
   }
 }