Split the PNaCl IRT shim into 3 pieces, and include one piece into IRT.

components/nacl/loader/nacl_listener.cc

 // Copyright 2013 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 "components/nacl/loader/nacl_listener.h"
 
 #include <errno.h>
 #include <stdlib.h>
 
 #if defined(OS_POSIX)
@@ skipping 334 matching lines @@
   args->enable_dyncode_syscalls = params.enable_dyncode_syscalls;
   if (!params.enable_dyncode_syscalls) {
     // Bound the initial nexe's code segment size under PNaCl to
     // reduce the chance of a code spraying attack succeeding (see
     // https://code.google.com/p/nativeclient/issues/detail?id=3572).
     // We assume that !params.enable_dyncode_syscalls is synonymous
     // with PNaCl.  We can't apply this arbitrary limit outside of
     // PNaCl because it might break existing NaCl apps, and this limit
     // is only useful if the dyncode syscalls are disabled.
     args->initial_nexe_max_code_bytes = 32 << 20;  // 32 MB
+
+    // Only enable the IRT shim ppapi hook for PNaCl pexes (not nexes).
+    // TODO(jvoung): Plumb through something indicating that this is PNaCl
+    // instead of relying on enable_dyncode_syscalls.
+    args->enable_irt_shim = 1;
   }
 #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
 
 #if defined(OS_LINUX)
   if (params.enable_nonsfi_mode) {
     nacl::nonsfi::MainStart(args->imc_bootstrap_handle);
     NOTREACHED();
     return;
   }
 #endif
   NaClChromeMainStartApp(nap, args);
   NOTREACHED();
 }