Convert mojo::system::ChannelEndpointClient to use our new refcounting stuff (instead of base's).

mojo/edk/system/message_pipe_dispatcher.h

Index: mojo/edk/system/message_pipe_dispatcher.h
diff --git a/mojo/edk/system/message_pipe_dispatcher.h b/mojo/edk/system/message_pipe_dispatcher.h
index cfe80a51f3f1369f194c721454079013e9b54b0d..bfc7997a42ea382ac23a5637b77db185c0a21676 100644
--- a/mojo/edk/system/message_pipe_dispatcher.h
+++ b/mojo/edk/system/message_pipe_dispatcher.h
@@ -42,7 +42,7 @@ class MessagePipeDispatcher final : public Dispatcher {
       MojoCreateMessagePipeOptions* out_options);
 
   // Must be called before any other methods. (This method is not thread-safe.)
-  void Init(scoped_refptr<MessagePipe> message_pipe,
+  void Init(RefPtr<MessagePipe>&& message_pipe,
             unsigned port) MOJO_NOT_THREAD_SAFE;
 
   // |Dispatcher| public methods:
@@ -110,7 +110,7 @@ class MessagePipeDispatcher final : public Dispatcher {
       MOJO_NOT_THREAD_SAFE;
 
   // This will be null if closed.
-  scoped_refptr<MessagePipe> message_pipe_ MOJO_GUARDED_BY(mutex());
+  RefPtr<MessagePipe> message_pipe_ MOJO_GUARDED_BY(mutex());
   unsigned port_ MOJO_GUARDED_BY(mutex());
 
   MOJO_DISALLOW_COPY_AND_ASSIGN(MessagePipeDispatcher);