Mojo: Add a "GetType()" to Dispatchers.

mojo/system/message_pipe_dispatcher.h

Index: mojo/system/message_pipe_dispatcher.h
diff --git a/mojo/system/message_pipe_dispatcher.h b/mojo/system/message_pipe_dispatcher.h
index 8101613313f0aecb127f24ac364fa690b9fb8242..1bfabc7e559f1263a2fd19b56fc0ba9b86e0f1a9 100644
--- a/mojo/system/message_pipe_dispatcher.h
+++ b/mojo/system/message_pipe_dispatcher.h
@@ -25,6 +25,8 @@ class MOJO_SYSTEM_IMPL_EXPORT MessagePipeDispatcher : public Dispatcher {
   // Must be called before any other methods. (This method is not thread-safe.)
   void Init(scoped_refptr<MessagePipe> message_pipe, unsigned port);
 
+  virtual Type GetType() OVERRIDE;
+
  private:
   friend class base::RefCountedThreadSafe<MessagePipeDispatcher>;
   virtual ~MessagePipeDispatcher();