Clean up header files.

base/process/process_handle_freebsd.cc

 // Copyright (c) 2011 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 "base/macros.h"
 #include "base/process/process_handle.h"
 
+#include <limits.h>
 #include <stddef.h>
 #include <sys/sysctl.h>
 #include <sys/types.h>
 #include <sys/user.h>
 #include <unistd.h>
 
 namespace base {
 
 ProcessId GetParentProcessId(ProcessHandle process) {
   struct kinfo_proc info;
@@ skipping 15 matching lines @@
 
   if (sysctl(mib, arraysize(mib), pathname, &length, NULL, 0) < 0 ||
       length == 0) {
     return FilePath();
   }
 
   return FilePath(std::string(pathname));
 }
 
 }  // namespace base