Add getters for callbacks on StreamController.

sdk/lib/async/broadcast_stream_controller.dart

Index: sdk/lib/async/broadcast_stream_controller.dart
diff --git a/sdk/lib/async/broadcast_stream_controller.dart b/sdk/lib/async/broadcast_stream_controller.dart
index e5a1efc777d0e212c2ea3ae37b2622d024f5a071..6f4ddab11c5156fe17302360b3052d655d63b7a6 100644
--- a/sdk/lib/async/broadcast_stream_controller.dart
+++ b/sdk/lib/async/broadcast_stream_controller.dart
@@ -79,8 +79,8 @@ abstract class _BroadcastStreamController<T>
   static const int _STATE_CLOSED = 4;
   static const int _STATE_ADDSTREAM = 8;
 
-  _NotificationHandler _onListen;
-  _NotificationHandler _onCancel;
+  ControllerCallback onListen;
+  ControllerCancelCallback onCancel;
 
   // State of the controller.
   int _state;
@@ -107,24 +107,30 @@ abstract class _BroadcastStreamController<T>
    */
   _Future _doneFuture;
 
-  _BroadcastStreamController(this._onListen, this._onCancel)
+  _BroadcastStreamController(this.onListen, this.onCancel)
       : _state = _STATE_INITIAL {
     _next = _previous = this;
   }
 
-  void set onListen(void onListenHandler()) { _onListen = onListenHandler; }
+  ControllerCallback get onPause {
+    throw new UnsupportedError(
+        "Broadcast stream controllers do not support pause callbacks");
+  }
 
   void set onPause(void onPauseHandler()) {
     throw new UnsupportedError(
         "Broadcast stream controllers do not support pause callbacks");
   }
 
-  void set onResume(void onResumeHandler())  {
+  ControllerCallback get onResume {
     throw new UnsupportedError(
         "Broadcast stream controllers do not support pause callbacks");
   }
 
-  void set onCancel(onCancelHandler()) { _onCancel = onCancelHandler; }
+  void set onResume(void onResumeHandler())  {
+    throw new UnsupportedError(
+        "Broadcast stream controllers do not support pause callbacks");
+  }
 
   // StreamController interface.
 
@@ -209,7 +215,7 @@ abstract class _BroadcastStreamController<T>
     _addListener(subscription);
     if (identical(_next, _previous)) {
       // Only one listener, so it must be the first listener.
-      _runGuarded(_onListen);
+      _runGuarded(onListen);
     }
     return subscription;
   }
@@ -310,7 +316,7 @@ abstract class _BroadcastStreamController<T>
 
     // Get event id of this event.
     int id = (_state & _STATE_EVENT_ID);
-    // Start firing (set the _STATE_FIRING bit). We don't do [_onCancel]
+    // Start firing (set the _STATE_FIRING bit). We don't do [onCancel]
     // callbacks while firing, and we prevent reentrancy of this function.
     //
     // Set [_state]'s event id to the next event's id.
@@ -346,7 +352,7 @@ abstract class _BroadcastStreamController<T>
       // When closed, _doneFuture is not null.
       _doneFuture._asyncComplete(null);
     }
-    _runGuarded(_onCancel);
+    _runGuarded(onCancel);
   }
 }