Revert of Get rid of UnsafeCurrent in Sampler

src/profiler/sampler.h

Index: src/profiler/sampler.h
diff --git a/src/profiler/sampler.h b/src/profiler/sampler.h
index f6804f8e25f7aa0a328a64b746cd8251115cad90..dcd1255d7578a8c8da60dcab9cf34ce78c48aca5 100644
--- a/src/profiler/sampler.h
+++ b/src/profiler/sampler.h
@@ -92,11 +92,6 @@
   // Whether the sampler is running (that is, consumes resources).
   bool IsActive() const { return base::NoBarrier_Load(&active_); }
 
-  // CpuProfiler collects samples by calling DoSample directly
-  // without calling Start. To keep it working, we register the sampler
-  // with the CpuProfiler.
-  bool IsRegistered() const { return base::NoBarrier_Load(&registered_); }
-
   void DoSample();
   // If true next sample must be initiated on the profiler event processor
   // thread right after latest sample is processed.
@@ -124,14 +119,11 @@
  private:
   void SetActive(bool value) { base::NoBarrier_Store(&active_, value); }
 
-  void SetRegistered(bool value) { base::NoBarrier_Store(&registered_, value); }
-
   Isolate* isolate_;
   const int interval_;
   base::Atomic32 profiling_;
   base::Atomic32 has_processing_thread_;
   base::Atomic32 active_;
-  base::Atomic32 registered_;
   PlatformData* data_;  // Platform specific data.
   // Counts stack samples taken in various VM states.
   bool is_counting_samples_;