Update from https://crrev.com/305340

sandbox/linux/services/syscall_wrappers.h

+// 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.
+
+#ifndef SANDBOX_LINUX_SERVICES_SYSCALL_WRAPPERS_H_
+#define SANDBOX_LINUX_SERVICES_SYSCALL_WRAPPERS_H_
+
+#include <sys/types.h>
+
+#include "sandbox/sandbox_export.h"
+
+namespace sandbox {
+
+// Provide direct system call wrappers for a few common system calls.
+// These are guaranteed to perform a system call and do not rely on things such
+// as caching the current pid (c.f. getpid()).
+
+SANDBOX_EXPORT pid_t sys_getpid(void);
+
+SANDBOX_EXPORT pid_t sys_gettid(void);
+
+SANDBOX_EXPORT long sys_clone(unsigned long flags);
+
+// |regs| is not supported and must be passed as nullptr.
+SANDBOX_EXPORT long sys_clone(unsigned long flags,
+                              void* child_stack,
+                              pid_t* ptid,
+                              pid_t* ctid,
+                              decltype(nullptr) regs);
+
+SANDBOX_EXPORT void sys_exit_group(int status);
+
+}  // namespace sandbox
+
+#endif  // SANDBOX_LINUX_SERVICES_SYSCALL_WRAPPERS_H_