Get rid of most instance of 'foo == NULL'

core/src/fpdfapi/fpdf_parser/fpdf_parser_decode.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 <limits.h>
 
 #include "core/include/fpdfapi/fpdf_module.h"
 #include "core/include/fpdfapi/fpdf_parser.h"
@@ skipping 436 matching lines @@
           i += 2;
           if (unicode == 0x1b) {
             break;
           }
         }
       } else {
         dest_buf[dest_pos++] = unicode;
       }
     }
     result.ReleaseBuffer(dest_pos);
-  } else if (pCharMap == NULL) {
+  } else if (!pCharMap) {
     FX_WCHAR* dest_buf = result.GetBuffer(src_len);
     for (FX_DWORD i = 0; i < src_len; i++) {
       dest_buf[i] = PDFDocEncoding[src_data[i]];
     }
     result.ReleaseBuffer(src_len);
   } else {
     return (*pCharMap->m_GetWideString)(
         pCharMap, CFX_ByteString((const FX_CHAR*)src_data, src_len));
   }
   return result;
 }
 CFX_ByteString PDF_EncodeText(const FX_WCHAR* pString,
                               int len,
                               CFX_CharMap* pCharMap) {
   if (len == -1) {
     len = FXSYS_wcslen(pString);
   }
   CFX_ByteString result;
-  if (pCharMap == NULL) {
+  if (!pCharMap) {
     FX_CHAR* dest_buf1 = result.GetBuffer(len);
     int i;
     for (i = 0; i < len; i++) {
       int code;
       for (code = 0; code < 256; code++)
         if (PDFDocEncoding[code] == pString[i]) {
           break;
         }
       if (code == 256) {
         break;
@@ skipping 81 matching lines @@
                      FX_DWORD src_size,
                      uint8_t*& dest_buf,
                      FX_DWORD& dest_size) {
   CCodec_ModuleMgr* pEncoders = CPDF_ModuleMgr::Get()->GetCodecModule();
   if (pEncoders) {
     return pEncoders->GetFlateModule()->FlateOrLZWDecode(
         FALSE, src_buf, src_size, FALSE, 0, 0, 0, 0, 0, dest_buf, dest_size);
   }
   return 0;
 }