[dart:io] Namespaces for file IO

runtime/bin/process_macos.cc

Index: runtime/bin/process_macos.cc
diff --git a/runtime/bin/process_macos.cc b/runtime/bin/process_macos.cc
index c888730d03bac892eec7d495770ac86a35fe1ece..d947e5a92cbb470de4573350476bcc939b87c007 100644
--- a/runtime/bin/process_macos.cc
+++ b/runtime/bin/process_macos.cc
@@ -24,6 +24,7 @@
 #include "bin/fdutils.h"
 #include "bin/lockers.h"
 #include "bin/log.h"
+#include "bin/namespace.h"
 #include "bin/thread.h"
 
 #include "platform/signal_blocker.h"
@@ -739,7 +740,8 @@ class ProcessStarter {
   DISALLOW_IMPLICIT_CONSTRUCTORS(ProcessStarter);
 };
 
-int Process::Start(const char* path,
+int Process::Start(Namespace* namespc,
+                   const char* path,
                    char* arguments[],
                    intptr_t arguments_length,
                    const char* working_directory,