When launching PNaCl helper nexes, explicitly disable IRT loading.

chrome/browser/nacl_host/nacl_process_host.h

Index: chrome/browser/nacl_host/nacl_process_host.h
diff --git a/chrome/browser/nacl_host/nacl_process_host.h b/chrome/browser/nacl_host/nacl_process_host.h
index 46337c476986d09691440664adc301b4766408c6..88bc968ffdf6608cd16707f750b20da863f27593 100644
--- a/chrome/browser/nacl_host/nacl_process_host.h
+++ b/chrome/browser/nacl_host/nacl_process_host.h
@@ -50,6 +50,7 @@ class NaClProcessHost : public content::BrowserChildProcessHostDelegate {
   NaClProcessHost(const GURL& manifest_url,
                   int render_view_id,
                   uint32 permission_bits,
+                  bool uses_irt,
                   bool off_the_record);
   virtual ~NaClProcessHost();
 
@@ -194,6 +195,8 @@ class NaClProcessHost : public content::BrowserChildProcessHostDelegate {
   bool enable_exception_handling_;
   bool enable_debug_stub_;
 
+  bool uses_irt_;
+
   bool off_the_record_;
 
   bool enable_ipc_proxy_;