Fix TSAN error in skia/chromium ref count debug checks

skia/config/sk_ref_cnt_ext_debug.h

Index: skia/config/sk_ref_cnt_ext_debug.h
diff --git a/skia/config/sk_ref_cnt_ext_debug.h b/skia/config/sk_ref_cnt_ext_debug.h
index b2b66adba729b8110d5b285c7e30cabfaa1af426..78a39a3789f23cb5cbc2a9f23c74a60ec4a5c5ae 100644
--- a/skia/config/sk_ref_cnt_ext_debug.h
+++ b/skia/config/sk_ref_cnt_ext_debug.h
@@ -9,23 +9,31 @@
 #error Only one SkRefCnt should be used.
 #endif
 
+#include <atomic>
+
 // Alternate implementation of SkRefCnt for Chromium debug builds
 class SK_API SkRefCnt : public SkRefCntBase {
 public:
-  SkRefCnt() : flags_(0) {}
-  void ref() const { SkASSERT(flags_ != AdoptionRequired_Flag); SkRefCntBase::ref(); }
+  SkRefCnt();
+  ~SkRefCnt() override;
+  void ref() const { SkASSERT(flags_.load() != AdoptionRequired_Flag); SkRefCntBase::ref(); }
   void adopted() const { flags_ |= Adopted_Flag; }
   void requireAdoption() const { flags_ |= AdoptionRequired_Flag; }
   void deref() const { SkRefCntBase::unref(); }
 private:
+
   enum {
     Adopted_Flag = 0x1,
     AdoptionRequired_Flag = 0x2,
   };
 
-  mutable int flags_;
+  mutable std::atomic<int> flags_;
 };
 
+inline SkRefCnt::SkRefCnt() : flags_(0) { }
+
+inline SkRefCnt::~SkRefCnt() { }
+
 // Bootstrap for Blink's WTF::RefPtr
 
 namespace WTF {