Update from https://crrev.com/327068

sandbox/linux/system_headers/arm_linux_ucontext.h

Index: sandbox/linux/system_headers/arm_linux_ucontext.h
diff --git a/sandbox/linux/system_headers/arm_linux_ucontext.h b/sandbox/linux/system_headers/arm_linux_ucontext.h
new file mode 100644
index 0000000000000000000000000000000000000000..0eb723a236bf0767b518c151d09c4d27a42e2c25
--- /dev/null
+++ b/sandbox/linux/system_headers/arm_linux_ucontext.h
@@ -0,0 +1,67 @@
+// Copyright (c) 2012 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_SYSTEM_HEADERS_ARM_LINUX_UCONTEXT_H_
+#define SANDBOX_LINUX_SYSTEM_HEADERS_ARM_LINUX_UCONTEXT_H_
+
+#if !defined(__BIONIC_HAVE_UCONTEXT_T)
+#if !defined(__native_client_nonsfi__)
+#include <asm/sigcontext.h>
+#else
+// In PNaCl toolchain, sigcontext and stack_t is not defined. So here declare
+// them.
+struct sigcontext {
+  unsigned long trap_no;
+  unsigned long error_code;
+  unsigned long oldmask;
+  unsigned long arm_r0;
+  unsigned long arm_r1;
+  unsigned long arm_r2;
+  unsigned long arm_r3;
+  unsigned long arm_r4;
+  unsigned long arm_r5;
+  unsigned long arm_r6;
+  unsigned long arm_r7;
+  unsigned long arm_r8;
+  unsigned long arm_r9;
+  unsigned long arm_r10;
+  unsigned long arm_fp;
+  unsigned long arm_ip;
+  unsigned long arm_sp;
+  unsigned long arm_lr;
+  unsigned long arm_pc;
+  unsigned long arm_cpsr;
+  unsigned long fault_address;
+};
+
+typedef struct sigaltstack {
+  void* ss_sp;
+  int ss_flags;
+  size_t ss_size;
+} stack_t;
+
+#endif
+
+// We also need greg_t for the sandbox, include it in this header as well.
+typedef unsigned long greg_t;
+
+// typedef unsigned long sigset_t;
+typedef struct ucontext {
+  unsigned long uc_flags;
+  struct ucontext* uc_link;
+  stack_t uc_stack;
+  struct sigcontext uc_mcontext;
+  sigset_t uc_sigmask;
+  /* Allow for uc_sigmask growth.  Glibc uses a 1024-bit sigset_t.  */
+  int __not_used[32 - (sizeof(sigset_t) / sizeof(int))];
+  /* Last for extensibility.  Eight byte aligned because some
+     coprocessors require eight byte alignment.  */
+  unsigned long uc_regspace[128] __attribute__((__aligned__(8)));
+} ucontext_t;
+
+#else
+#include <sys/ucontext.h>
+#endif  // __BIONIC_HAVE_UCONTEXT_T
+
+#endif  // SANDBOX_LINUX_SYSTEM_HEADERS_ARM_LINUX_UCONTEXT_H_