Added toMultiSubscriber on Stream.

sdk/lib/async/stream.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.
 
 part of dart.async;
 
 // -------------------------------------------------------------------
 // Core Stream types
 // -------------------------------------------------------------------
 
@@ skipping 14 matching lines @@
   }
 
   /**
    * Creates a single-subscription stream that gets its data from [data].
    */
   factory Stream.fromIterable(Iterable<T> data) {
     return new _IterableSingleStreamImpl<T>(data);
   }
 
   /**
+   * Returns a multi-subscription stream that produces the same events as this.
+   *
+   * If this stream is single-subscription, return a new stream that allows
+   * multiple subscribers. It will subscribe to this stream when its first
+   * subscriber is added, and unsubscribe again when the last subscription is
+   * cancelled.
+   *
+   * If this stream is already multi-subscriber, it is returned unmodified.
+   */
+  Stream<T> asMultiSubscriberStream();
+
+  /**
    * Stream that outputs events from the [sources] in cyclic order.
    *
    * The merged streams are paused and resumed in order to ensure the proper
    * order of output events.
    */
   factory Stream.cyclic(Iterable<Stream> sources) {
     return new CyclicScheduleStream<T>(sources);
   }
 
  /**
@@ skipping 795 matching lines @@
     sink.signalError(error);
   }
 
   /**
    * Handle an incoming done event.
    */
   void handleDone(StreamSink<T> sink) {
     sink.close();
   }
 }