Expose v8 context a MessagePort lives in to give content side code a valid context to (de)serialize…

Source/core/dom/MessagePort.h

 /*
  * Copyright (C) 2008 Apple Inc. All Rights Reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 94 matching lines @@
     // A port gets neutered when it is transferred to a new owner via postMessage().
     bool isNeutered() const { return !m_entangledChannel; }
 
     virtual void trace(Visitor*) override;
 
 private:
     explicit MessagePort(ExecutionContext&);
 
     // WebMessagePortChannelClient implementation.
     virtual void messageAvailable() override;
+    virtual v8::Isolate* scriptIsolate() override;
+    virtual v8::Handle<v8::Context> scriptContext() override;

[adamk, 2015/02/18 02:01:21]

Exposing a Context like this through the API worries me a little bit, as it's
easy to mishandle Contexts (memory leaks and security issues).

I looked at your Chromium change, but I'm not very familiar with
V8ValueConverter or base::Value; perhaps you can outline the high-level need you
have here?

     void dispatchMessages();
 
     OwnPtr<WebMessagePortChannel> m_entangledChannel;
 
     bool m_started;
     bool m_closed;
 
     WeakPtrFactory<MessagePort> m_weakFactory;
 };
 
 } // namespace blink
 
 #endif // MessagePort_h