Update mojo sdk to rev f6c8ec07c01deebc13178d516225fd12695c3dc2

mojo/public/cpp/utility/lib/thread_local_posix.cc

 // 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.
 
 #include "mojo/public/cpp/utility/lib/thread_local.h"
 
 #include <assert.h>
 
 namespace mojo {
 namespace internal {
 
 // static
 void ThreadLocalPlatform::AllocateSlot(SlotType* slot) {
-  if (pthread_key_create(slot, NULL) != 0) {
+  if (pthread_key_create(slot, nullptr) != 0) {
     assert(false);
   }
 }
 
 // static
 void ThreadLocalPlatform::FreeSlot(SlotType slot) {
   if (pthread_key_delete(slot) != 0) {
     assert(false);
   }
 }
 
 // static
 void* ThreadLocalPlatform::GetValueFromSlot(SlotType slot) {
   return pthread_getspecific(slot);
 }
 
 // static
 void ThreadLocalPlatform::SetValueInSlot(SlotType slot, void* value) {
   if (pthread_setspecific(slot, value) != 0) {
     assert(false);
   }
 }
 
 }  // namespace internal
 }  // namespace mojo