Mojo: Remove MessagePipe::OnRemove(); instead just use MessagePipe::Close().

mojo/system/message_pipe.h

Index: mojo/system/message_pipe.h
diff --git a/mojo/system/message_pipe.h b/mojo/system/message_pipe.h
index 7d86d5f4a233a484bb961ab045acc802f6118d4b..5375302269fe368715794785c75902748d9c85fc 100644
--- a/mojo/system/message_pipe.h
+++ b/mojo/system/message_pipe.h
@@ -95,10 +95,6 @@ class MOJO_SYSTEM_IMPL_EXPORT MessagePipe
   MojoResult EnqueueMessage(unsigned port,
                             scoped_ptr<MessageInTransit> message);
 
-  // This is used by |Channel|. TODO(vtl): Rename it (and have the
-  // |ChannelEndpoint| call it instead).
-  void OnRemove(unsigned port);
-
  private:
   MessagePipe();