Update from https://crrev.com/327068

sandbox/linux/seccomp-bpf/trap_unittest.cc

+// Copyright 2015 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 "sandbox/linux/seccomp-bpf/trap.h"
+
+#include <signal.h>
+
+#include "sandbox/linux/tests/unit_tests.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace sandbox {
+namespace {
+
+#if !defined(THREAD_SANITIZER)
+SANDBOX_TEST_ALLOW_NOISE(Trap, SigSysAction) {
+  // This creates a global Trap instance, and registers the signal handler
+  // (Trap::SigSysAction).
+  Trap::Registry();
+
+  // Send SIGSYS to self. If signal handler (SigSysAction) is not registered,
+  // the process will be terminated with status code -SIGSYS.
+  // Note that, SigSysAction handler would output an error message
+  // "Unexpected SIGSYS received." so it is necessary to allow the noise.
+  raise(SIGSYS);
+}
+#endif
+
+}  // namespace
+}  // namespace sandbox