Accompany debugger commands with senders data

src/debug-agent.h

Index: src/debug-agent.h
===================================================================
--- src/debug-agent.h	(revision 1753)
+++ src/debug-agent.h	(working copy)
@@ -46,8 +46,14 @@
       : name_(StrDup(name)), port_(port),
         server_(OS::CreateSocket()), terminate_(false),
         session_access_(OS::CreateMutex()), session_(NULL),
-        terminate_now_(OS::CreateSemaphore(0)) {}
-  ~DebuggerAgent() { delete server_; }
+        terminate_now_(OS::CreateSemaphore(0)) {
+    ASSERT(instance_ == NULL);
+    instance_ = this;
+  }
+  ~DebuggerAgent() {
+     instance_ = NULL;
+     delete server_;
+  }
 
   void Shutdown();
 
@@ -66,9 +72,11 @@
   DebuggerAgentSession* session_;  // Current active session if any.
   Semaphore* terminate_now_;  // Semaphore to signal termination.
 
+  static DebuggerAgent* instance_;
+
   friend class DebuggerAgentSession;
   friend void DebuggerAgentMessageHandler(const uint16_t* message, int length,
-                                          void *data);
+                                          v8::Debug::ClientData* client_data);
 
   DISALLOW_COPY_AND_ASSIGN(DebuggerAgent);
 };