Move SkAtomics.h to private.

include/private/SkOncePtr.h

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkOncePtr_DEFINED
 #define SkOncePtr_DEFINED
 
-#include "SkAtomics.h"
+#include "../private/SkAtomics.h"
 #include "SkUniquePtr.h"
 
 template <typename T> class SkBaseOncePtr;
 
 // Use this to create a global static pointer that's intialized exactly once when you call get().
 #define SK_DECLARE_STATIC_ONCE_PTR(type, name) namespace {} static SkBaseOncePtr<type> name;
 
 // Use this for a local or member pointer that's initialized exactly once when you call get().
 template <typename T, typename Delete = skstd::default_delete<T>>
 class SkOncePtr : SkNoncopyable {
@@ skipping 75 matching lines @@
         // TODO: If state == 1 spin until it's not?
     }
 
     // fState == 0 --> we have not created our ptr yet
     // fState == 1 --> someone is in the middle of creating our ptr
     // else        --> (T*)fState is our ptr
     mutable uintptr_t fState;
 };
 
 #endif//SkOncePtr_DEFINED