XFA: more underlying type changes to match master

fpdfsdk/src/fpdfview.cpp

 // 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
 
 #include "public/fpdfview.h"
 
 #include "../include/fpdfxfa/fpdfxfa_app.h"
 #include "../include/fpdfxfa/fpdfxfa_doc.h"
@@ skipping 855 matching lines @@
       pContext->m_pContext, pContext->m_pDevice, pContext->m_pOptions);
   pContext->m_pRenderer->Start(pause);
   if (bNeedToRestore)
     pContext->m_pDevice->RestoreState();
 }
 
 DLLEXPORT int STDCALL FPDF_GetPageSizeByIndex(FPDF_DOCUMENT document,
                                               int page_index,
                                               double* width,
                                               double* height) {
-  CPDFXFA_Document* pDoc = (CPDFXFA_Document*)document;
-  if (pDoc == NULL)
+  UnderlyingDocumentType* pDoc = UnderlyingFromFPDFDocument(document);
+  if (!pDoc)
     return FALSE;
 
   int count = pDoc->GetPageCount();
   if (page_index < 0 || page_index >= count)
     return FALSE;
 
   CPDFXFA_Page* pPage = pDoc->GetPage(page_index);
   if (!pPage)
     return FALSE;
 
@@ skipping 126 matching lines @@
   str->len = 0;
   return 0;
 }
 
 DLLEXPORT FPDF_DEST STDCALL FPDF_GetNamedDest(FPDF_DOCUMENT document,
                                               int index,
                                               void* buffer,
                                               long* buflen) {
   if (!buffer)
     *buflen = 0;
-  if (!document || index < 0)
-    return NULL;
+
+  if (index < 0)
+    return nullptr;
 
   CPDF_Document* pDoc = CPDFDocumentFromFPDFDocument(document);
+  if (!pDoc)
+    return nullptr;
+
   CPDF_Dictionary* pRoot = pDoc->GetRoot();
   if (!pRoot)
-    return NULL;
+    return nullptr;
 
   CPDF_Object* pDestObj = NULL;
   CFX_ByteString bsName;
   CPDF_NameTree nameTree(pDoc, FX_BSTRC("Dests"));
   int count = nameTree.GetCount();
   if (index >= count) {
     CPDF_Dictionary* pDest = pRoot->GetDict(FX_BSTRC("Dests"));
     if (!pDest)
       return NULL;
     if (index >= count + pDest->GetCount())
@@ skipping 28 matching lines @@
   if (!buffer) {
     *buflen = len;
   } else if (*buflen >= len) {
     memcpy(buffer, utf16Name.c_str(), len);
     *buflen = len;
   } else {
     *buflen = -1;
   }
   return (FPDF_DEST)pDestObj;
 }