Add seccomp sandbox for non-SFI NaCl

sandbox/linux/seccomp-bpf-helpers/sigsys_handlers.h

 // Copyright (c) 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.
 
 #ifndef SANDBOX_LINUX_SECCOMP_BPF_HELPERS_SIGSYS_HANDLERS_H_
 #define SANDBOX_LINUX_SECCOMP_BPF_HELPERS_SIGSYS_HANDLERS_H_
 
 #include "base/basictypes.h"
 #include "build/build_config.h"
 #include "sandbox/linux/sandbox_export.h"
@@ skipping 21 matching lines @@
     SIGSYSCloneFailure(const struct arch_seccomp_data& args, void* aux);
 // The crashing address will be (option & 0xFFF), where option is the prctl(2)
 // argument.
 SANDBOX_EXPORT intptr_t
     SIGSYSPrctlFailure(const struct arch_seccomp_data& args, void* aux);
 // The crashing address will be request & 0xFFFF, where request is the ioctl(2)
 // argument.
 SANDBOX_EXPORT intptr_t
     SIGSYSIoctlFailure(const struct arch_seccomp_data& args, void* aux);
 
+// Following four functions return substrings of error messages used

[Mark Seaborn, 2014/04/15 23:03:14]

Nit: "The following..." (otherwise I start reading it as a verb instead of an
adjective)

[hamaji, 2014/04/16 02:10:48]

Done.

+// in the above four functions. They are useful in death tests.
+SANDBOX_EXPORT const char* GetErrorMessageContentForTests();
+SANDBOX_EXPORT const char* GetCloneErrorMessageContentForTests();
+SANDBOX_EXPORT const char* GetPrctlErrorMessageContentForTests();
+SANDBOX_EXPORT const char* GetIoctlErrorMessageContentForTests();
+
 }  // namespace sandbox.
 
 #endif  // SANDBOX_LINUX_SECCOMP_BPF_HELPERS_SIGSYS_HANDLERS_H_