Prepare for removal of source_filter.gypi:

runtime/bin/directory_win.cc

Index: runtime/bin/directory_win.cc
===================================================================
--- runtime/bin/directory_win.cc	(revision 18775)
+++ runtime/bin/directory_win.cc	(working copy)
@@ -2,10 +2,13 @@
 // 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/directory.h"
 
-#include <errno.h>
-#include <sys/stat.h>
+#include <errno.h>  // NOLINT
+#include <sys/stat.h>  // NOLINT
 
 #include "bin/log.h"
 
@@ -396,3 +399,5 @@
   free(const_cast<wchar_t*>(system_new_path));
   return (move_status != 0);
 }
+
+#endif  // defined(TARGET_OS_WINDOWS)