Update from https://crrev.com/304121

base/threading/platform_thread_linux.cc

 // 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.
 
 #include "base/threading/platform_thread.h"
 
 #include <errno.h>
 #include <sched.h>
 
 #include "base/lazy_instance.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/safe_strerror_posix.h"
 #include "base/threading/thread_id_name_manager.h"
 #include "base/threading/thread_restrictions.h"
 #include "base/tracked_objects.h"
 
 #if !defined(OS_NACL)
 #include <sys/prctl.h>
 #include <sys/resource.h>
 #include <sys/syscall.h>
 #include <sys/time.h>
 #include <unistd.h>
 #endif
 
 namespace base {
 
 namespace {
 
+#if !defined(OS_NACL)
 int ThreadNiceValue(ThreadPriority priority) {
   switch (priority) {
     case kThreadPriority_RealtimeAudio:
       return -10;
     case kThreadPriority_Background:
       return 10;
     case kThreadPriority_Normal:
       return 0;
     case kThreadPriority_Display:
       return -6;
     default:
       NOTREACHED() << "Unknown priority.";
       return 0;
   }
 }
+#endif  // !defined(OS_NACL)
 
 }  // namespace
 
 // static
 void PlatformThread::SetName(const char* name) {
   ThreadIdNameManager::GetInstance()->SetName(CurrentId(), name);
   tracked_objects::ThreadData::InitializeThreadContext(name);
 
 #if !defined(OS_NACL)
   // On linux we can get the thread names to show up in the debugger by setting
@@ skipping 55 matching lines @@
 #if !defined(THREAD_SANITIZER)
   return 0;
 #else
   // ThreadSanitizer bloats the stack heavily. Evidence has been that the
   // default stack size isn't enough for some browser tests.
   return 2 * (1 << 23);  // 2 times 8192K (the default stack size on Linux).
 #endif
 }
 
 }  // namespace base