Set up NaClChromeMainArgs number_of_cores member so apps can size threadpools appropriately

chrome/nacl/nacl_listener.cc

Index: chrome/nacl/nacl_listener.cc
diff --git a/chrome/nacl/nacl_listener.cc b/chrome/nacl/nacl_listener.cc
index 5f3ced4af92f8cea3ce22ca52e71717cb3aa5f02..913c087d883d339361482698896c05fa44953fc6 100644
--- a/chrome/nacl/nacl_listener.cc
+++ b/chrome/nacl/nacl_listener.cc
@@ -7,6 +7,10 @@
 #include <errno.h>
 #include <stdlib.h>
 
+#if defined(OS_LINUX) || defined(OS_MACOSX)
+#include <unistd.h>
+#endif
+
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
@@ -147,6 +151,9 @@ NaClListener::NaClListener() : shutdown_event_(true, false),
   DCHECK(g_listener == NULL);
   g_listener = this;
 #endif
+#if defined(OS_LINUX) || defined(OS_MACOSX)
+  number_of_cores_ = sysconf(_SC_NPROCESSORS_ONLN);
+#endif
 }
 
 NaClListener::~NaClListener() {
@@ -226,6 +233,7 @@ void NaClListener::OnStart(const nacl::NaClStartParams& params) {
     LOG(ERROR) << "Failed to dup() the urandom FD";
     return;
   }
+  args->number_of_cores = number_of_cores_;
   args->create_memory_object_func = CreateMemoryObject;
 # if defined(OS_MACOSX)
   CHECK(handles.size() >= 1);