Optionally have MessagePort pass data as base::Value, part 1.

content/browser/message_port_message_filter.h

 // Copyright 2013 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.
 
 #ifndef CONTENT_BROWSER_MESSAGE_PORT_MESSAGE_FILTER_H_
 #define CONTENT_BROWSER_MESSAGE_PORT_MESSAGE_FILTER_H_
 
 #include "base/callback.h"
 #include "content/common/content_export.h"
 #include "content/public/browser/browser_message_filter.h"
@@ skipping 22 matching lines @@
 
   // BrowserMessageFilter implementation.
   void OnChannelClosing() override;
   bool OnMessageReceived(const IPC::Message& message) override;
   void OnDestruct() const override;
 
   int GetNextRoutingID();
 
   // MessagePortDelegate implementation.
   void SendMessage(int route_id,
-                   const base::string16& message,
+                   const MessagePortMessage& message,
                    const std::vector<int>& sent_message_port_ids) override;
   void SendMessagesAreQueued(int route_id) override;
 
   // Updates message ports registered for |message_port_ids| and returns
   // new routing IDs for the updated ports via |new_routing_ids|.
   void UpdateMessagePortsWithNewRoutes(
       const std::vector<int>& message_port_ids,
       std::vector<int>* new_routing_ids);
 
   void RouteMessageEventWithMessagePorts(
@@ skipping 14 matching lines @@
   // This is guaranteed to be valid until OnChannelClosing is invoked, and it's
   // not used after.
   NextRoutingIDCallback next_routing_id_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(MessagePortMessageFilter);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_WORKER_MESSAGE_FILTER_H_