Make CFX_WideString(const CFX_WideString&) explicit.

xfa/fxbarcode/oned/BC_OnedCode39Writer.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
 // Original code is licensed as follows:
 /*
  * Copyright 2010 ZXing authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
@@ skipping 323 matching lines @@
   for (int32_t i = 0; i < codeWidth / 2; i++) {
     result[i] ^= result[codeWidth - 1 - i];
     result[codeWidth - 1 - i] ^= result[i];
     result[i] ^= result[codeWidth - 1 - i];
   }
   return result;
 }
 CFX_WideString CBC_OnedCode39Writer::encodedContents(
     const CFX_WideStringC& contents,
     int32_t& e) {
-  CFX_WideString encodedContents = contents;
+  CFX_WideString encodedContents(contents);
   if (m_bCalcChecksum && m_bPrintChecksum) {
     CFX_WideString checksumContent = FilterContents(contents);
     CFX_ByteString str = checksumContent.UTF8Encode();
     FX_CHAR checksum;
     checksum = CalcCheckSum(str, e);
-    BC_EXCEPTION_CHECK_ReturnValue(e, FX_WSTRC(L""));
+    BC_EXCEPTION_CHECK_ReturnValue(e, CFX_WideString());
     str += checksum;
     encodedContents += checksum;
   }
   return encodedContents;
 }
 void CBC_OnedCode39Writer::RenderResult(const CFX_WideStringC& contents,
                                         uint8_t* code,
                                         int32_t codeLength,
                                         FX_BOOL isDevice,
                                         int32_t& e) {
   CFX_WideString encodedCon = encodedContents(contents, e);
   BC_EXCEPTION_CHECK_ReturnVoid(e);
   CBC_OneDimWriter::RenderResult(encodedCon.AsStringC(), code, codeLength,
                                  isDevice, e);
 }