When launching PNaCl helper nexes, explicitly disable IRT loading.

chrome/nacl/nacl_listener.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/nacl/nacl_listener.h"
 
 #include <errno.h>
 #include <stdlib.h>
 
 #include "base/command_line.h"
@@ skipping 216 matching lines @@
     return;
   }
   args->create_memory_object_func = CreateMemoryObject;
 # if defined(OS_MACOSX)
   CHECK(handles.size() >= 1);
   g_shm_fd = nacl::ToNativeHandle(handles[handles.size() - 1]);
   handles.pop_back();
 # endif
 #endif
 
-  CHECK(handles.size() >= 1);
-  NaClHandle irt_handle = nacl::ToNativeHandle(handles[handles.size() - 1]);
-  handles.pop_back();
+  if (params.uses_irt) {
+    CHECK(handles.size() >= 1);
+    NaClHandle irt_handle = nacl::ToNativeHandle(handles[handles.size() - 1]);
+    handles.pop_back();
 
 #if defined(OS_WIN)
-  args->irt_fd = _open_osfhandle(reinterpret_cast<intptr_t>(irt_handle),
-                                 _O_RDONLY | _O_BINARY);
-  if (args->irt_fd < 0) {
-    LOG(ERROR) << "_open_osfhandle() failed";
-    return;
+    args->irt_fd = _open_osfhandle(reinterpret_cast<intptr_t>(irt_handle),
+                                   _O_RDONLY | _O_BINARY);
+    if (args->irt_fd < 0) {
+      LOG(ERROR) << "_open_osfhandle() failed";
+      return;
+    }
+#else
+    args->irt_fd = irt_handle;
+#endif
+  } else {
+    // Otherwise, the IRT handle is not even sent.
+    args->irt_fd = -1;
   }
-#else
-  args->irt_fd = irt_handle;
-#endif
 
   if (params.validation_cache_enabled) {
     // SHA256 block size.
     CHECK_EQ(params.validation_cache_key.length(), (size_t) 64);
     // The cache structure is not freed and exists until the NaCl process exits.
     args->validation_cache = CreateValidationCache(
         new BrowserValidationDBProxy(this), params.validation_cache_key,
         params.version);
   }
 
   CHECK(handles.size() == 1);
   args->imc_bootstrap_handle = nacl::ToNativeHandle(handles[0]);
   args->enable_exception_handling = params.enable_exception_handling;
   args->enable_debug_stub = params.enable_debug_stub;
 #if defined(OS_LINUX) || defined(OS_MACOSX)
   args->debug_stub_server_bound_socket_fd = nacl::ToNativeHandle(
       params.debug_stub_server_bound_socket);
 #endif
 #if defined(OS_WIN)
   args->broker_duplicate_handle_func = BrokerDuplicateHandle;
   args->attach_debug_exception_handler_func = AttachDebugExceptionHandler;
 #endif
 #if defined(OS_LINUX)
   args->prereserved_sandbox_size = prereserved_sandbox_size_;
 #endif
   NaClChromeMainStart(args);
   NOTREACHED();
 }