Update mojo sdk to rev f6c8ec07c01deebc13178d516225fd12695c3dc2

mojo/public/cpp/utility/tests/mutex_unittest.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/mutex.h"
 
 #include <stdlib.h>  // For |rand()|.
 #include <time.h>  // For |nanosleep()| (defined by POSIX).
 
 #include <vector>
@@ skipping 72 matching lines @@
     }
   }
 
  private:
   static void SleepALittle() {
     static const long kNanosPerMilli = 1000000;
     struct timespec req = {
       0,  // Seconds.
       (rand() % 10) * kNanosPerMilli // Nanoseconds.
     };
-    int rv = nanosleep(&req, NULL);
+    int rv = nanosleep(&req, nullptr);
     MOJO_ALLOW_UNUSED_LOCAL(rv);
     assert(rv == 0);
   }
 
   const size_t times_to_lock_;
   const Type type_;
   const bool should_sleep_;
   Mutex* const mutex_;
   int* const shared_value_;
 
@@ skipping 146 matching lines @@
   // Destroy lock with lock held.
   EXPECT_DEATH_IF_SUPPORTED({
     Mutex mutex;
     mutex.Lock();
   }, "");
 }
 #endif  // !defined(NDEBUG)
 
 }  // namespace
 }  // namespace mojo