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 b98b742e45f2a358c7031c23c7dbf11cbadadc62..80a63cbc14db68e952460c088978f4f66f2f9e7d 100644
--- a/chrome/browser/nacl_host/nacl_process_host.h
+++ b/chrome/browser/nacl_host/nacl_process_host.h
@@ -50,7 +50,8 @@ class NaClProcessHost : public content::BrowserChildProcessHostDelegate {
   NaClProcessHost(const GURL& manifest_url,
                   int render_view_id,
                   uint32 permission_bits,
-                  bool off_the_record);
+                  bool off_the_record,
+                  bool uses_irt);
   virtual ~NaClProcessHost();
 
   // Do any minimal work that must be done at browser startup.
@@ -199,6 +200,8 @@ class NaClProcessHost : public content::BrowserChildProcessHostDelegate {
 
   bool enable_ipc_proxy_;
 
+  bool uses_irt_;
+
   // Channel proxy to terminate the NaCl-Browser PPAPI channel.
   scoped_ptr<IPC::ChannelProxy> ipc_proxy_channel_;
   // Plugin listener, to forward browser channel messages to us.