Clean up issues raised on previous CL.

src/isolate.cc

Index: src/isolate.cc
diff --git a/src/isolate.cc b/src/isolate.cc
index f2564f9f3eb83cfb1042b2d583b1295c03e88332..79a348b6e48d5914228945b7f2ac4cece59e7ecf 100644
--- a/src/isolate.cc
+++ b/src/isolate.cc
@@ -2288,7 +2288,6 @@ Isolate::Isolate(bool enable_serializer)
       bootstrapper_(NULL),
       runtime_profiler_(NULL),
       compilation_cache_(NULL),
-      counters_(NULL),
       logger_(NULL),
       stats_table_(NULL),
       load_stub_cache_(NULL),
@@ -2552,8 +2551,6 @@ Isolate::~Isolate() {
   delete logger_;
   logger_ = NULL;
 
-  counters_ = NULL;
-
   delete handle_scope_implementer_;
   handle_scope_implementer_ = NULL;
 
@@ -2637,14 +2634,9 @@ bool Isolate::PropagatePendingExceptionToExternalTryCatch() {
   return true;
 }
 
-static base::LazyMutex initialize_counters_mutex = LAZY_MUTEX_INITIALIZER;
-
 bool Isolate::InitializeCounters() {
-  if (counters_ != nullptr) return false;
-  base::LockGuard<base::Mutex> guard(initialize_counters_mutex.Pointer());
-  if (counters_ != nullptr) return false;
+  if (counters_shared_) return false;
   counters_shared_ = std::make_shared<Counters>(this);
-  counters_ = counters_shared_.get();
   return true;
 }
 
@@ -2864,7 +2856,8 @@ bool Isolate::Init(Deserializer* des) {
 StatsTable* Isolate::stats_table() {
   if (stats_table_ != nullptr) return stats_table_;
   InitializeCounters();
-  return stats_table_ = counters_->stats_table();
+  stats_table_ = counters_shared_->stats_table();
+  return stats_table_;
 }