Add ptr_util.h from base until std::make_unique<> available

core/fxcrt/fx_memory.h

 // Copyright 2014 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
 #ifndef CORE_FXCRT_FX_MEMORY_H_
 #define CORE_FXCRT_FX_MEMORY_H_
 
 #include "core/fxcrt/fx_system.h"
@@ skipping 83 matching lines @@
 struct FxFreeDeleter {
   inline void operator()(void* ptr) const { FX_Free(ptr); }
 };
 
 // Used with std::unique_ptr to Release() objects that can't be deleted.
 template <class T>
 struct ReleaseDeleter {
   inline void operator()(T* ptr) const { ptr->Release(); }
 };
 
-// Used to help transfer ownership of a raw pointer to std::unique_ptr.
-template <typename T>
-std::unique_ptr<T> WrapUnique(T* ptr) {
-  return std::unique_ptr<T>(ptr);
-}
-
 #endif  // __cplusplus
 
 #endif  // CORE_FXCRT_FX_MEMORY_H_