Prepare for removal of source_filter.gypi:

runtime/bin/dbg_connection_win.cc

Index: runtime/bin/dbg_connection_win.cc
===================================================================
--- runtime/bin/dbg_connection_win.cc	(revision 18775)
+++ runtime/bin/dbg_connection_win.cc	(working copy)
@@ -2,6 +2,9 @@
 // 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.
 
+#include "platform/globals.h"
+#if defined(TARGET_OS_WINDOWS)
+
 #include "bin/dbg_connection.h"
 
 #include "bin/eventhandler.h"
@@ -39,3 +42,5 @@
   ClientSocket* client_socket = reinterpret_cast<ClientSocket*>(socket);
   return recv(client_socket->socket(), buf, len, 0);
 }
+
+#endif  // defined(TARGET_OS_WINDOWS)