[cpu-profiler][cleanup] Use std::atomic_bool for running flag

Mechanical change to use std:: atomics instead.

Change-Id: If64cc972eb247c93e7080e9eb764cbc6b2cf35ce
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2172966Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Peter Marshall <petermarshall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67487}

src/profiler/cpu-profiler.cc

@@ -85,7 +85,6 @@ ProfilerEventsProcessor::ProfilerEventsProcessor(
     : Thread(Thread::Options("v8:ProfEvntProc", kProfilerStackSize)),
       generator_(generator),
       code_observer_(code_observer),
-      running_(1),
       last_code_event_id_(0),
       last_processed_code_event_id_(0),
       isolate_(isolate) {
@@ -150,7 +149,10 @@ void ProfilerEventsProcessor::AddSample(TickSample sample) {
 }
 
 void ProfilerEventsProcessor::StopSynchronously() {
-  if (!base::Relaxed_AtomicExchange(&running_, 0)) return;
+  bool expected = true;
+  if (!running_.compare_exchange_strong(expected, false,
+                                        std::memory_order_relaxed))
+    return;
   {
     base::MutexGuard guard(&running_mutex_);
     running_cond_.NotifyOne();
@@ -225,7 +227,7 @@ SamplingEventsProcessor::ProcessOneSample() {
 
 void SamplingEventsProcessor::Run() {
   base::MutexGuard guard(&running_mutex_);
-  while (!!base::Relaxed_Load(&running_)) {
+  while (running_.load(std::memory_order_relaxed)) {
     base::TimeTicks nextSampleTime =
         base::TimeTicks::HighResolutionNow() + period_;
     base::TimeTicks now;
@@ -262,7 +264,7 @@ void SamplingEventsProcessor::Run() {
           // If true was returned, we got interrupted before the timeout
           // elapsed. If this was not due to a change in running state, a
           // spurious wakeup occurred (thus we should continue to wait).
-          if (!base::Relaxed_Load(&running_)) {
+          if (!running_.load(std::memory_order_relaxed)) {
             break;
           }
           now = base::TimeTicks::HighResolutionNow();
@@ -288,7 +290,7 @@ void SamplingEventsProcessor::SetSamplingInterval(base::TimeDelta period) {
   StopSynchronously();
 
   period_ = period;
-  base::Relaxed_Store(&running_, 1);
+  running_.store(true, std::memory_order_relaxed);
 
   StartSynchronously();
 }

src/profiler/cpu-profiler.h

@@ -5,10 +5,9 @@
 #ifndef V8_PROFILER_CPU_PROFILER_H_
 #define V8_PROFILER_CPU_PROFILER_H_
 
+#include <atomic>
 #include <memory>
 
-#include "src/base/atomic-utils.h"
-#include "src/base/atomicops.h"
 #include "src/base/platform/condition-variable.h"
 #include "src/base/platform/mutex.h"
 #include "src/base/platform/time.h"
@@ -164,7 +163,7 @@ class V8_EXPORT_PRIVATE ProfilerEventsProcessor : public base::Thread,
   // Thread control.
   void Run() override = 0;
   void StopSynchronously();
-  V8_INLINE bool running() { return !!base::Relaxed_Load(&running_); }
+  bool running() { return running_.load(std::memory_order_relaxed); }
   void Enqueue(const CodeEventsContainer& event);
 
   // Puts current stack into the tick sample events buffer.
@@ -191,8 +190,7 @@ class V8_EXPORT_PRIVATE ProfilerEventsProcessor : public base::Thread,
 
   ProfileGenerator* generator_;
   ProfilerCodeObserver* code_observer_;
-  // TODO(petermarshall): Use std::atomic and remove imports.
-  base::Atomic32 running_;
+  std::atomic_bool running_{true};
   base::ConditionVariable running_cond_;
   base::Mutex running_mutex_;
   LockedQueue<CodeEventsContainer> events_buffer_;