Update pkg/http to use the new async APIs.

pkg/http/lib/src/multipart_request.dart

 // Copyright (c) 2012, 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 multipart_request;
 
 import 'dart:async';
 import 'dart:io';
 import 'dart:math';
 import 'dart:uri';
 import 'dart:utf';
 
 import 'base_request.dart';
+import 'byte_stream.dart';
 import 'multipart_file.dart';
 import 'utils.dart';
 
 /// A `multipart/form-data` request. Such a request has both string [fields],
 /// which function as normal form fields, and (potentially streamed) binary
 /// [files].
 ///
 /// This request automatically sets the Content-Type header to
 /// `multipart/form-data` and the Content-Transfer-Encoding header to `binary`.
 /// These values will override any values set by the user.
@@ skipping 20 matching lines @@
   /// [fields] and [files] and cannot be set manually.
   int get contentLength {
     var length = 0;
 
     fields.forEach((name, value) {
       length += "--".length + _BOUNDARY_LENGTH + "\r\n".length +
           _headerForField(name, value).length +
           encodeUtf8(value).length + "\r\n".length;
     });
 
-    for (var file in files) {
+    for (var file in _files.collection) {
       length += "--".length + _BOUNDARY_LENGTH + "\r\n".length +
           _headerForFile(file).length +
           file.length + "\r\n".length;
     }
 
     return length + "--".length + _BOUNDARY_LENGTH + "--\r\n".length;
   }
 
   set contentLength(int value) {
     throw new UnsupportedError("Cannot set the contentLength property of "
         "multipart requests.");
   }
 
   /// The form fields to send for this request.
   final Map<String, String> fields;
 
-  /// The files to upload for this request.
-  final List<MultipartFile> files;
+  /// The sink for files to upload for this request.
+  ///
+  /// This doesn't need to be closed. When the request is sent, whichever files
+  /// are written to this sink at that point will be used.
+  Sink<MultipartFile> get files => _files;
+
+  /// The private version of [files], typed so that the underlying collection is
+  /// accessible.
+  final CollectionSink<MultipartFile> _files;
 
   /// Creates a new [MultipartRequest].
   MultipartRequest(String method, Uri url)
     : super(method, url),
       fields = <String>{},
-      files = <MultipartFile>[];
+      _files = new CollectionSink<MultipartFile>(<MultipartFile>[]);
 
-  /// Freezes all mutable fields and returns an [InputStream] that will emit the
-  /// request body.
-  InputStream finalize() {
+  /// Freezes all mutable fields and returns a single-subscription [ByteStream]
+  /// that will emit the request body.
+  ByteStream finalize() {
     // TODO(nweiz): freeze fields and files
     var boundary = _boundaryString(_BOUNDARY_LENGTH);
     headers['content-type'] = 'multipart/form-data; boundary="$boundary"';
     headers['content-transfer-encoding'] = 'binary';
     super.finalize();
 
-    var stream = new ListInputStream();
+    var controller = new StreamController<List<int>>.singleSubscription();
 
     void writeAscii(String string) {
       assert(isPlainAscii(string));
-      stream.write(string.charCodes);
+      controller.add(string.charCodes);
     }
 
-    void writeUtf8(String string) => stream.write(encodeUtf8(string));
-    void writeLine() => stream.write([13, 10]); // \r\n
+    writeUtf8(String string) => controller.add(encodeUtf8(string));
+    writeLine() => controller.add([13, 10]); // \r\n
 
     fields.forEach((name, value) {
       writeAscii('--$boundary\r\n');
       writeAscii(_headerForField(name, value));
       writeUtf8(value);
       writeLine();
     });
 
-    Futures.forEach(files, (file) {
+    Futures.forEach(_files.collection, (file) {
       writeAscii('--$boundary\r\n');
       writeAscii(_headerForFile(file));
-      return writeInputToInput(file.finalize(), stream)
+      return writeStreamToSink(file.finalize(), controller)
         .then((_) => writeLine());
     }).then((_) {
       // TODO(nweiz): pass any errors propagated through this future on to
       // the stream. See issue 3657.
       writeAscii('--$boundary--\r\n');
-      stream.markEndOfStream();
+      controller.close();
     });
 
-    return stream;
+    return new ByteStream(controller);
   }
 
   /// All character codes that are valid in multipart boundaries. From
   /// http://tools.ietf.org/html/rfc2046#section-5.1.1.
   static final List<int> _BOUNDARY_CHARACTERS = const <int>[
     39, 40, 41, 43, 95, 44, 45, 46, 47, 58, 61, 63, 48, 49, 50, 51, 52, 53, 54,
     55, 56, 57, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80,
     81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 97, 98, 99, 100, 101, 102, 103,
     104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118,
     119, 120, 121, 122
@@ skipping 29 matching lines @@
   String _boundaryString(int length) {
     var prefix = "dart-http-boundary-";
     var list = new List<int>.fixedLength(length - prefix.length);
     for (var i = 0; i < list.length; i++) {
       list[i] = _BOUNDARY_CHARACTERS[
           _random.nextInt(_BOUNDARY_CHARACTERS.length)];
     }
     return "$prefix${new String.fromCharCodes(list)}";
   }
 }