Add stack chain support to pkg/watcher and pkg/http.

pkg/watcher/lib/src/directory_watcher/mac_os.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.
 
 library watcher.directory_watcher.mac_os;
 
 import 'dart:async';
 import 'dart:io';
 
 import '../constructable_file_system_event.dart';
@@ skipping 55 matching lines @@
   ///
   /// These are gathered together so that they may all be canceled when the
   /// watcher is closed. This does not include [_watchSubscription].
   final _subscriptions = new Set<StreamSubscription>();
 
   _MacOSDirectoryWatcher(String directory)
       : directory = directory,
         _files = new PathSet(directory) {
     _startWatch();
 
-    _listen(new Directory(directory).list(recursive: true),
+    _listen(Chain.track(new Directory(directory).list(recursive: true)),
         (entity) {
       if (entity is! Directory) _files.add(entity.path);
     },
         onError: _emitError,
         onDone: _readyCompleter.complete,
         cancelOnError: true);
   }
 
   void close() {
     for (var subscription in _subscriptions) {
@@ skipping 15 matching lines @@
           _eventsBasedOnFileSystem(path) : [canonicalEvent];
 
       for (var event in events) {
         if (event is FileSystemCreateEvent) {
           if (!event.isDirectory) {
             _emitEvent(ChangeType.ADD, path);
             _files.add(path);
             continue;
           }
 
-          _listen(new Directory(path).list(recursive: true), (entity) {
+          _listen(Chain.track(new Directory(path).list(recursive: true)),
+              (entity) {
             if (entity is Directory) return;
             _emitEvent(ChangeType.ADD, entity.path);
             _files.add(entity.path);
           }, onError: _emitError, cancelOnError: true);
         } else if (event is FileSystemModifyEvent) {
           assert(!event.isDirectory);
           _emitEvent(ChangeType.MODIFY, path);
         } else {
           assert(event is FileSystemDeleteEvent);
           for (var removedPath in _files.remove(path)) {
@@ skipping 184 matching lines @@
     for (var file in _files.toSet()) {
       _emitEvent(ChangeType.REMOVE, file);
     }
     _files.clear();
     close();
   }
 
   /// Start or restart the underlying [Directory.watch] stream.
   void _startWatch() {
     // Batch the FSEvent changes together so that we can dedup events.
-    var innerStream = new Directory(directory).watch(recursive: true).transform(
-        new BatchedStreamTransformer<FileSystemEvent>());
+    var innerStream =
+        Chain.track(new Directory(directory).watch(recursive: true))
+        .transform(new BatchedStreamTransformer<FileSystemEvent>());
     _watchSubscription = innerStream.listen(_onBatch,
         onError: _eventsController.addError,
         onDone: _onDone);
   }
 
   /// Emit an event with the given [type] and [path].
   void _emitEvent(ChangeType type, String path) {
     if (!isReady) return;
 
     // Don't emit ADD events for files that we already know about. Such an event
@@ skipping 15 matching lines @@
   void _listen(Stream stream, void onData(event), {Function onError,
       void onDone(), bool cancelOnError}) {
     var subscription;
     subscription = stream.listen(onData, onError: onError, onDone: () {
       _subscriptions.remove(subscription);
       if (onDone != null) onDone();
     }, cancelOnError: cancelOnError);
     _subscriptions.add(subscription);
   }
 }