When launching PNaCl helper nexes, explicitly disable IRT loading.

ppapi/native_client/src/trusted/plugin/sel_ldr_launcher_chrome.cc

Index: ppapi/native_client/src/trusted/plugin/sel_ldr_launcher_chrome.cc
diff --git a/ppapi/native_client/src/trusted/plugin/sel_ldr_launcher_chrome.cc b/ppapi/native_client/src/trusted/plugin/sel_ldr_launcher_chrome.cc
index 8da1aeb3e10fa6bbac359b732ea39eddb10a7b80..b9e13a5d78f1f7daf75f9719677bddcb83f6da29 100644
--- a/ppapi/native_client/src/trusted/plugin/sel_ldr_launcher_chrome.cc
+++ b/ppapi/native_client/src/trusted/plugin/sel_ldr_launcher_chrome.cc
@@ -11,13 +11,14 @@ LaunchNaClProcessFunc launch_nacl_process = NULL;
 namespace plugin {
 
 bool SelLdrLauncherChrome::Start(const char* url) {
-  return Start(0, url, true, false);
+  return Start(0, url, true, false, true);
 }
 
 bool SelLdrLauncherChrome::Start(PP_Instance instance,
                                  const char* url,
                                  bool uses_ppapi,
-                                 bool enable_ppapi_dev) {
+                                 bool enable_ppapi_dev,
+                                 bool uses_irt) {
   if (!launch_nacl_process)
     return false;
   // send a synchronous message to the browser process
@@ -28,6 +29,7 @@ bool SelLdrLauncherChrome::Start(PP_Instance instance,
                           PP_FromBool(uses_ppapi),
                           PP_FromBool(enable_ppapi_dev),
                           kNumberOfChannelsToBeCreated,
+                          PP_FromBool(uses_irt),
                           &channel_) != PP_NACL_OK) {
     return false;
   }