Remove custom memory manager

core/src/fpdfapi/fpdf_edit/fpdf_edit_doc.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 "../../../include/fpdfapi/fpdf_page.h"
 #include "../../../include/fpdfapi/fpdf_module.h"
 #include "../fpdf_page/pageint.h"
 #include <limits.h>
@@ skipping 525 matching lines @@
         iLength = FXSYS_strlen(pLang);
     }
     FX_UINT32 uHash = FX_GetLangHashCode(pLang);
     return FX_GetCsFromLangCode(uHash);
 }
 static void _CFString2CFXByteString(CFStringRef src, CFX_ByteString &dest)
 {
     SInt32 len =  CFStringGetLength(src);
     CFRange range = CFRangeMake(0, len);
     CFIndex used = 0;
-    UInt8* pBuffer = (UInt8*)malloc(sizeof(UInt8) * (len + 1));
-    FXSYS_memset32(pBuffer, 0, sizeof(UInt8) * (len + 1));
+    UInt8* pBuffer = (UInt8*)calloc(len+1, sizeof(UInt8));
     CFStringGetBytes(src, range, kCFStringEncodingASCII, 0, false, pBuffer, len, &used);
     dest = (FX_LPSTR)pBuffer;
     free(pBuffer);
 }
 FX_BOOL IsHasCharSet(CFArrayRef languages, const CFX_DWordArray &charSets)
 {
     int iCount = charSets.GetSize();
     for (int i = 0; i < CFArrayGetCount(languages); ++i) {
         CFStringRef language = (CFStringRef)CFArrayGetValueAtIndex(languages, i);
         FX_DWORD CharSet = FX_GetCharsetFromLang(CFStringGetCStringPtr(language, kCFStringEncodingMacRoman), -1);
@@ skipping 638 matching lines @@
 void FPDFAPI_FlatPageAttr(CPDF_Dictionary* pPageDict, FX_BSTR name)
 {
     if (pPageDict->KeyExist(name)) {
         return;
     }
     CPDF_Object* pObj = FPDFAPI_GetPageAttr(pPageDict, name);
     if (pObj) {
         pPageDict->SetAt(name, pObj->Clone());
     }
 }