Include <unistd.h> in base/process/internal_linux.h.

base/process/internal_linux.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.
 
 // This file contains internal routines that are called by other files in
 // base/process/.
 
 #ifndef BASE_PROCESS_LINUX_INTERNAL_H_
 #define BASE_PROCESS_LINUX_INTERNAL_H_
 
+#include <unistd.h>
+
 #include "base/files/file_path.h"
 
 namespace base {
 
 class Time;
 class TimeDelta;
 
 namespace internal {
 
 // "/proc"
@@ skipping 59 matching lines @@
 // Returns the time that the OS started. Clock ticks are relative to this.
 Time GetBootTime();
 
 // Converts Linux clock ticks to a wall time delta.
 TimeDelta ClockTicksToTimeDelta(int clock_ticks);
 
 }  // namespace internal
 }  // namespace base
 
 #endif  // BASE_PROCESS_LINUX_INTERNAL_H_