Simplify implementation of Mutex.

src/sampler.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 397 matching lines @@
 
 
 class SamplerThread : public Thread {
  public:
   static const int kSamplerThreadStackSize = 64 * KB;
 
   explicit SamplerThread(int interval)
       : Thread(Thread::Options("SamplerThread", kSamplerThreadStackSize)),
         interval_(interval) {}
 
-  static void SetUp() { if (!mutex_) mutex_ = OS::CreateMutex(); }
+  static void SetUp() { if (!mutex_) mutex_ = new Mutex; }
   static void TearDown() { delete mutex_; }
 
   static void AddActiveSampler(Sampler* sampler) {
     bool need_to_start = false;
     ScopedLock lock(mutex_);
     if (instance_ == NULL) {
       // Start a thread that will send SIGPROF signal to VM threads,
       // when CPU profiling will be enabled.
       instance_ = new SamplerThread(sampler->interval());
       need_to_start = true;
@@ skipping 267 matching lines @@
   sample->Init(isolate_, state);
   if (is_counting_samples_) {
     if (sample->state == JS || sample->state == EXTERNAL) {
       ++js_and_external_sample_count_;
     }
   }
   Tick(sample);
 }
 
 } }  // namespace v8::internal