Use smart pointers for class owned pointers under xfa/fde

xfa/fgas/crt/fgas_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 XFA_FGAS_CRT_FGAS_MEMORY_H_
 #define XFA_FGAS_CRT_FGAS_MEMORY_H_
 
+#include <memory>
+
 #include "core/fxcrt/include/fx_memory.h"
 #include "core/fxcrt/include/fx_system.h"
 
 enum FX_ALLOCTYPE {
   FX_ALLOCTYPE_Static,
   FX_ALLOCTYPE_Fixed,
 };
 
 class IFX_MemoryAllocator {
  public:
   virtual ~IFX_MemoryAllocator() {}
   virtual void* Alloc(size_t size) = 0;
   virtual void Free(void* pBlock) = 0;
 
-  static IFX_MemoryAllocator* Create(FX_ALLOCTYPE eType,
-                                     size_t chunkSize,
-                                     size_t blockSize);
+  static std::unique_ptr<IFX_MemoryAllocator> Create(FX_ALLOCTYPE eType,
+                                                     size_t chunkSize,
+                                                     size_t blockSize);
 };
 
 class CFX_Target {
  public:
   virtual ~CFX_Target() {}
   void* operator new(size_t size) { return FX_Alloc(uint8_t, size); }
   void operator delete(void* p) { FX_Free(p); }
   void* operator new(size_t size, IFX_MemoryAllocator* pAllocator) {
     return pAllocator->Alloc(size);
   }
   void operator delete(void* p, IFX_MemoryAllocator* pAllocator) {
     pAllocator->Free(p);
   }
   void* operator new(size_t size, void* place) { return place; }
   void operator delete(void* p, void* place) {}
 };
 
 #define FXTARGET_NewWith(__allocator__) new (__allocator__)
 #define FXTARGET_DeleteWith(__class__, __allocator__, pointer) \
   {                                                            \
     (pointer)->~__class__();                                   \
     (pointer)->operator delete((pointer), (__allocator__));    \
   }
 
 #endif  // XFA_FGAS_CRT_FGAS_MEMORY_H_