Enable one PID namespace per process for NaCl processes.

components/nacl/loader/nonsfi/irt_exception_handling.cc

 // Copyright 2014 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 <errno.h>
 #include <pthread.h>
 #include <signal.h>
 
 #include "components/nacl/loader/nonsfi/irt_interfaces.h"
 #include "native_client/src/include/nacl_macros.h"
@@ skipping 31 matching lines @@
   if (signal_handler_function_pointer) {
     NaClSignalContext signal_context;
     NaClSignalContextFromHandler(&signal_context, uc);
     NaClExceptionFrame exception_frame;
     NaClSignalSetUpExceptionFrame(&exception_frame,
                                   &signal_context,
                                   0 /* context_user_addr,
                                        not useful for NonSFI NaCl. */);
     signal_handler_function_pointer(&exception_frame.context);
   }
-  _exit(-1);
+  _exit(-sig);
 }
 
 int IrtExceptionHandler(NaClExceptionHandler handler,
                                NaClExceptionHandler* old_handler) {
   pthread_mutex_lock(&mutex);
   if (old_handler)
     *old_handler = signal_handler_function_pointer;
   signal_handler_function_pointer = handler;
   pthread_mutex_unlock(&mutex);
   return 0;
@@ skipping 38 matching lines @@
 
   // Install all handlers.
   for (a = 0; a < NACL_ARRAY_SIZE(kSignals); a++) {
     if (sigaction(kSignals[a], &sa, NULL) != 0)
       NaClLog(LOG_FATAL, "sigaction to register signals failed.\n");
   }
 }
 
 }  // namespace nonsfi
 }  // namespace nacl