Beginnings of a debugger wire protocol

runtime/bin/dbg_connection.h

Index: runtime/bin/dbg_connection.h
===================================================================
--- runtime/bin/dbg_connection.h	(revision 0)
+++ runtime/bin/dbg_connection.h	(revision 0)
@@ -0,0 +1,67 @@
+// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+#ifndef BIN_DBG_CONNECTION_H_
+#define BIN_DBG_CONNECTION_H_
+
+#include "bin/builtin.h"
+#include "bin/utils.h"
+
+#include "include/dart_debugger_api.h"
+
+#include "platform/globals.h"
+#include "platform/thread.h"
+// Declare the OS-specific types ahead of defining the generic class.
+#if defined(TARGET_OS_LINUX)
+#include "bin/dbg_connection_linux.h"
+#elif defined(TARGET_OS_MACOS)
+#include "bin/dbg_connection_macos.h"
+#elif defined(TARGET_OS_WINDOWS)
+#include "bin/dbg_connection_win.h"
+#else
+#error Unknown target os.
+#endif
+
+
+class MessageBuffer;
+
+class DebuggerConnectionHandler {
+ public:
+  ~DebuggerConnectionHandler();
+  static void StartHandler(const char* address, int port_number);
+
+  static bool IsConnected() {
+    return debugger_fd_ >= 0;
+  }
+
+ private:
+  static void SendBreakpointEvent(Dart_Breakpoint bpt, Dart_StackTrace trace);
+  static void BreakpointHandler(Dart_Breakpoint bpt, Dart_StackTrace trace);
+
+  static void AcceptDbgConnection(int debug_fd);
+  static void CloseDbgConnection();
+
+  static void HandleMessages();
+  static void HandleResumeCmd();
+
+  static bool handler_started_;
+
+  // The socket that is listening for incoming debugger connections.
+  // This descriptor is created and closed by a VM thread.
+  static int listener_fd_;
+
+  // The socket that connects with the debugger client.
+  // The descriptor is created by the debugger connection thread and
+  // closed by a VM thread.
+  static int debugger_fd_;
+
+  static MessageBuffer* msgbuf_;
+
+  friend class DebuggerConnectionImpl;
+
+  DISALLOW_ALLOCATION();
+  DISALLOW_IMPLICIT_CONSTRUCTORS(DebuggerConnectionHandler);
+};
+
+#endif  // BIN_DBG_CONNECTION_H_