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

fpdfsdk/fpdfxfa/fpdfxfa_app.cpp

Index: fpdfsdk/fpdfxfa/fpdfxfa_app.cpp
diff --git a/fpdfsdk/fpdfxfa/fpdfxfa_app.cpp b/fpdfsdk/fpdfxfa/fpdfxfa_app.cpp
index 88c31ef006f9ec027ed2915511973586d0adb4fe..4edfcf0676d55026dc5231f927b20ed3b9b584a0 100644
--- a/fpdfsdk/fpdfxfa/fpdfxfa_app.cpp
+++ b/fpdfsdk/fpdfxfa/fpdfxfa_app.cpp
@@ -11,6 +11,7 @@
 #include "fpdfsdk/cpdfsdk_environment.h"
 #include "fpdfsdk/fpdfxfa/fpdfxfa_util.h"
 #include "fpdfsdk/fsdk_define.h"
+#include "third_party/base/ptr_util.h"
 #include "xfa/fxbarcode/BC_Library.h"
 #include "xfa/fxfa/xfa_ffapp.h"
 #include "xfa/fxfa/xfa_fontmgr.h"
@@ -56,7 +57,7 @@ FX_BOOL CPDFXFA_App::Initialize(v8::Isolate* pIsolate) {
   if (!m_pIsolate)
     return FALSE;
 
-  m_pXFAApp = WrapUnique(new CXFA_FFApp(this));
+  m_pXFAApp = pdfium::MakeUnique<CXFA_FFApp>(this);
   m_pXFAApp->SetDefaultFontMgr(
       std::unique_ptr<CXFA_DefFontMgr>(new CXFA_DefFontMgr));