Add DebugMessageDispatchHandler

src/debug.h

Index: src/debug.h
diff --git a/src/debug.h b/src/debug.h
index ec6a23bc8b9b333b151ae942fbaf9ee6f0439f19..c5c6b5ee56a55227ac6598b028ee4d901c51487e 100644
--- a/src/debug.h
+++ b/src/debug.h
@@ -629,6 +629,8 @@ class Debugger {
   static void SetMessageHandler(v8::Debug::MessageHandler2 handler);
   static void SetHostDispatchHandler(v8::Debug::HostDispatchHandler handler,
                                      int period);
+  static void SetDebugMessageDispatchHandler(
+      v8::Debug::DebugMessageDispatchHandler handler);
 
   // Invoke the message handler function.
   static void InvokeMessageHandler(MessageImpl message);
@@ -689,6 +691,7 @@ class Debugger {
   static v8::Debug::MessageHandler2 message_handler_;
   static bool debugger_unload_pending_;  // Was message handler cleared?
   static v8::Debug::HostDispatchHandler host_dispatch_handler_;
+  static v8::Debug::DebugMessageDispatchHandler debug_message_dispatch_handler_;
   static int host_dispatch_micros_;
 
   static DebuggerAgent* agent_;