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

public/platform/WebMessagePortChannelClient.h

Index: public/platform/WebMessagePortChannelClient.h
diff --git a/public/platform/WebMessagePortChannelClient.h b/public/platform/WebMessagePortChannelClient.h
index 9389338bc37d6c01d478ca50332773e55574cf69..79cb9ba1d404c3598f498bdf400d51b7c0dcb4a2 100644
--- a/public/platform/WebMessagePortChannelClient.h
+++ b/public/platform/WebMessagePortChannelClient.h
@@ -31,10 +31,17 @@
 #ifndef WebMessagePortChannelClient_h
 #define WebMessagePortChannelClient_h
 
+namespace v8 {
+class Context;
+template<typename T> class Handle;
+class Isolate;
+}
+
 namespace blink {
 
 // Provides an interface for users of WebMessagePortChannel to be notified
-// when messages are available.
+// when messages are available. This also gives users of WebMessagePortChannel
+// access to the V8 Context this message port lives in.
 class WebMessagePortChannelClient {
 public:
     // Alerts that new messages have arrived, which are retrieved by calling
@@ -42,6 +49,12 @@ public:
     // on any thread.
     virtual void messageAvailable() = 0;
 
+    // Returns the V8 isolate this message port lives in.
+    virtual v8::Isolate* scriptIsolate() = 0;
+
+    // Returns the V8 context this message port lives in.
+    virtual v8::Handle<v8::Context> scriptContext() = 0;
+
 protected:
     ~WebMessagePortChannelClient() { }
 };