Rename unsubscribe to cancel.

sdk/lib/async/stream_controller.dart

Index: sdk/lib/async/stream_controller.dart
diff --git a/sdk/lib/async/stream_controller.dart b/sdk/lib/async/stream_controller.dart
index b9c54b975e43f49efcdeaa4caef299aa7a32a3e0..a60ca8167ab43c0e32d3d580e3f5ed36c9d5dffb 100644
--- a/sdk/lib/async/stream_controller.dart
+++ b/sdk/lib/async/stream_controller.dart
@@ -56,14 +56,14 @@ class StreamController<T> extends Stream<T> implements StreamSink<T> {
                                              onPauseStateChange);
   }
 
-  StreamSubscription subscribe({void onData(T data),
-                                void onError(AsyncError error),
-                                void onDone(),
-                                bool unsubscribeOnError}) {
-    return _stream.subscribe(onData: onData,
-                             onError: onError,
-                             onDone: onDone,
-                             unsubscribeOnError: unsubscribeOnError);
+  StreamSubscription listen(void onData(T data),
+                            { void onError(AsyncError error),
+                              void onDone(),
+                              bool unsubscribeOnError}) {
+    return _stream.listen(onData,
+                          onError: onError,
+                          onDone: onDone,
+                          unsubscribeOnError: unsubscribeOnError);
   }
 
   /**