Revert of Remove SkThread.h, include SkMutex.h or SkAtomics.h as appropriate.

bench/RefCntBench.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #include <memory>
 #include "Benchmark.h"
-#include "SkAtomics.h"
 #include "SkRefCnt.h"
+#include "SkThread.h"
 #include "SkWeakRefCnt.h"
 
 enum {
     M = 2
 };
 
 class AtomicInc32 : public Benchmark {
 public:
     AtomicInc32() : fX(0) {}
 
@@ skipping 219 matching lines @@
 DEF_BENCH( return new AtomicInc32(); )
 DEF_BENCH( return new AtomicInc64(); )
 
 DEF_BENCH( return new RefCntBench_Stack(); )
 DEF_BENCH( return new RefCntBench_Heap(); )
 DEF_BENCH( return new RefCntBench_New(); )
 
 DEF_BENCH( return new WeakRefCntBench_Stack(); )
 DEF_BENCH( return new WeakRefCntBench_Heap(); )
 DEF_BENCH( return new WeakRefCntBench_New(); )