Prepare for removal of source_filter.gypi:

runtime/bin/platform_macos.cc

 // 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.
 
+#include "platform/globals.h"
+#if defined(TARGET_OS_MACOS)
+
 #include "bin/platform.h"
 
-#include <crt_externs.h>
-#include <signal.h>
-#include <string.h>
-#include <unistd.h>
+#include <crt_externs.h>  // NOLINT
+#include <signal.h>  // NOLINT
+#include <string.h>  // NOLINT
+#include <unistd.h>  // NOLINT
 
 
 bool Platform::Initialize() {
   // Turn off the signal handler for SIGPIPE as it causes the process
   // to terminate on writing to a closed pipe. Without the signal
   // handler error EPIPE is set instead.
   struct sigaction act;
   bzero(&act, sizeof(act));
   act.sa_handler = SIG_IGN;
   if (sigaction(SIGPIPE, &act, 0) != 0) {
@@ skipping 42 matching lines @@
   for (intptr_t current = 0; current < i; current++) {
     result[current] = environ[current];
   }
   return result;
 }
 
 
 void Platform::FreeEnvironment(char** env, intptr_t count) {
   delete[] env;
 }
+
+#endif  // defined(TARGET_OS_MACOS)