Adding a router class to handle messages that expect responses.

mojo/bindings/java/src/org/chromium/mojo/bindings/MessageReceiver.java

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.mojo.bindings;
 
 /**
  * A class which implements this interface can receive {@link Message} objects.
  */
 public interface MessageReceiver {
 
     /**
-     * Receive a {@link Message}. The {@link MessageReceiver} is allowed to mutable the message.
-     * Returns |true| if the message has been handled, |false| otherwise.
+     * Receive a {@link MessageWithHeader}. The {@link MessageReceiver} is allowed to mutable the
+     * message. Returns |true| if the message has been handled, |false| otherwise.
      */
-    boolean accept(Message message);
+    boolean accept(MessageWithHeader message);
 }