Use boolean instead of Atomic32 for is_profiling_ flag

src/cpu-profiler.h

 // Copyright 2012 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 227 matching lines @@
   static void CodeCreateEvent(Logger::LogEventsAndTags tag,
                               Code* code, int args_count);
   static void CodeMovingGCEvent() {}
   static void CodeMoveEvent(Address from, Address to);
   static void CodeDeleteEvent(Address from);
   static void GetterCallbackEvent(String* name, Address entry_point);
   static void RegExpCodeCreateEvent(Code* code, String* source);
   static void SetterCallbackEvent(String* name, Address entry_point);
   static void SharedFunctionInfoMoveEvent(Address from, Address to);
 
-  // TODO(isolates): this doesn't have to use atomics anymore.
-
   static INLINE(bool is_profiling(Isolate* isolate)) {
     CpuProfiler* profiler = isolate->cpu_profiler();
-    return profiler != NULL && NoBarrier_Load(&profiler->is_profiling_);
+    return profiler != NULL && profiler->is_profiling_;
   }
 
  private:
   CpuProfiler();
   ~CpuProfiler();
   void StartCollectingProfile(const char* title);
   void StartCollectingProfile(String* title);
   void StartProcessorIfNotStarted();
   CpuProfile* StopCollectingProfile(const char* title);
   CpuProfile* StopCollectingProfile(Object* security_token, String* title);
   void StopProcessorIfLastProfile(const char* title);
   void StopProcessor();
   void ResetProfiles();
 
   CpuProfilesCollection* profiles_;
   unsigned next_profile_uid_;
   TokenEnumerator* token_enumerator_;
   ProfileGenerator* generator_;
   ProfilerEventsProcessor* processor_;
   int saved_logging_nesting_;
   bool need_to_stop_sampler_;
-  Atomic32 is_profiling_;
+  bool is_profiling_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(CpuProfiler);
 };
 
 } }  // namespace v8::internal
 
 
 #endif  // V8_CPU_PROFILER_H_