Reimplement profiler sampler on Mac OS X to get it working under Chromium.

src/platform.h

 // Copyright 2006-2008 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 492 matching lines @@
   EmbeddedVector<Address, kMaxFramesCount> stack;  // Call stack.
   int frames_count;  // Number of captured frames.
 };
 
 class Sampler {
  public:
   // Initialize sampler.
   explicit Sampler(int interval, bool profiling);
   virtual ~Sampler();
 
+  // Performs stack sampling.
+  virtual void SampleStack(TickSample* sample) = 0;
+
   // This method is called for each sampling period with the current
   // program counter.
   virtual void Tick(TickSample* sample) = 0;
 
   // Start and stop sampler.
   void Start();
   void Stop();
 
   // Is the sampler used for profiling.
   inline bool IsProfiling() { return profiling_; }
 
   // Whether the sampler is running (that is, consumes resources).
   inline bool IsActive() { return active_; }
 
   class PlatformData;
 
  private:
-  int interval_;
-  bool profiling_;
+  const int interval_;
+  const bool profiling_;
   bool active_;
   PlatformData* data_;  // Platform specific data.
   DISALLOW_IMPLICIT_CONSTRUCTORS(Sampler);
 };
 
 #endif  // ENABLE_LOGGING_AND_PROFILING
 
 } }  // namespace v8::internal
 
 #endif  // V8_PLATFORM_H_