Fix TSAN error in skia/chromium ref count debug checks

skia/config/sk_ref_cnt_ext_debug.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef SK_REF_CNT_EXT_DEBUG_H_
 #define SK_REF_CNT_EXT_DEBUG_H_
 
 #ifdef SK_REF_CNT_EXT_RELEASE_H_
 #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 {
   inline void adopted(const SkRefCnt* object) {
     if (!object)
       return;
     object->adopted();
   }
   inline void requireAdoption(const SkRefCnt* object) {
     if (!object)
       return;
     object->requireAdoption();
   }
 };
 
 using WTF::adopted;
 using WTF::requireAdoption;
 
 #endif