Remove NULL in xfa/

xfa/fxfa/app/xfa_ffapp.cpp

Index: xfa/fxfa/app/xfa_ffapp.cpp
diff --git a/xfa/fxfa/app/xfa_ffapp.cpp b/xfa/fxfa/app/xfa_ffapp.cpp
index 5f2f1b982851df40d587b3036826159b4bb0ce1a..dd760f617ea8cbbe0efe44dd6ac50b285806d3e5 100644
--- a/xfa/fxfa/app/xfa_ffapp.cpp
+++ b/xfa/fxfa/app/xfa_ffapp.cpp
@@ -121,20 +121,20 @@ CXFA_FFDoc* CXFA_FFApp::CreateDoc(IXFA_DocProvider* pProvider,
   FX_BOOL bSuccess = pDoc->OpenDoc(pStream, bTakeOverFile);
   if (!bSuccess) {
     delete pDoc;
-    pDoc = NULL;
+    pDoc = nullptr;
   }
   return pDoc;
 }
 CXFA_FFDoc* CXFA_FFApp::CreateDoc(IXFA_DocProvider* pProvider,
                                   CPDF_Document* pPDFDoc) {
-  if (pPDFDoc == NULL) {
-    return NULL;
+  if (!pPDFDoc) {
+    return nullptr;
   }
   CXFA_FFDoc* pDoc = new CXFA_FFDoc(this, pProvider);
   FX_BOOL bSuccess = pDoc->OpenDoc(pPDFDoc);
   if (!bSuccess) {
     delete pDoc;
-    pDoc = NULL;
+    pDoc = nullptr;
   }
   return pDoc;
 }