Prepare for removal of source_filter.gypi:

runtime/bin/log_macos.cc

Index: runtime/bin/log_macos.cc
===================================================================
--- runtime/bin/log_macos.cc	(revision 18775)
+++ runtime/bin/log_macos.cc	(working copy)
@@ -2,9 +2,12 @@
 // 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_MACOS)
+
 #include "bin/log.h"
 
-#include <stdio.h>
+#include <stdio.h>  // NOLINT
 
 void Log::VPrint(const char* format, va_list args) {
   vfprintf(stdout, format, args);
@@ -15,3 +18,5 @@
   vfprintf(stderr, format, args);
   fflush(stderr);
 }
+
+#endif  // defined(TARGET_OS_MACOS)