Convert SkRefCnt to std::atomic.

src/core/SkRWBuffer.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
+#include "SkAtomics.h"
 #include "SkRWBuffer.h"
 #include "SkStream.h"
 
 // Force small chunks to be a page's worth
 static const size_t kMinAllocSize = 4096;
 
 struct SkBufferBlock {
     SkBufferBlock*  fNext;
     size_t          fUsed;
     size_t          fCapacity;
@@ skipping 327 matching lines @@
     const SkROBuffer*   fBuffer;
     SkROBuffer::Iter    fIter;
     size_t              fLocalOffset;
     size_t              fGlobalOffset;
 };
 
 SkStreamAsset* SkRWBuffer::newStreamSnapshot() const {
     SkAutoTUnref<SkROBuffer> buffer(this->newRBufferSnapshot());
     return new SkROBufferStreamAsset(buffer);
 }