Use boolean instead of Atomic32 for is_profiling_ flag

The field is only accessed on the JS thread so it can be converted into bool.

BUG=None

Review URL: https://codereview.chromium.org/12340052

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13731 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/cpu-profiler.cc

@@ -491,7 +491,7 @@ void CpuProfiler::StartProcessorIfNotStarted() {
     isolate->logger()->logging_nesting_ = 0;
     generator_ = new ProfileGenerator(profiles_);
     processor_ = new ProfilerEventsProcessor(generator_);
-    NoBarrier_Store(&is_profiling_, true);
+    is_profiling_ = true;
     processor_->Start();
     // Enumerate stuff we already have in the heap.
     if (isolate->heap()->HasBeenSetUp()) {
@@ -552,7 +552,7 @@ void CpuProfiler::StopProcessor() {
     sampler->Stop();
     need_to_stop_sampler_ = false;
   }
-  NoBarrier_Store(&is_profiling_, false);
+  is_profiling_ = false;
   processor_->Stop();
   processor_->Join();
   delete processor_;

src/cpu-profiler.h

@@ -245,11 +245,9 @@ class CpuProfiler {
   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:
@@ -271,7 +269,7 @@ class CpuProfiler {
   ProfilerEventsProcessor* processor_;
   int saved_logging_nesting_;
   bool need_to_stop_sampler_;
-  Atomic32 is_profiling_;
+  bool is_profiling_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(CpuProfiler);