Make down-conversion explicit from CFX_ByteString to CFX_ByteStringC.

core/fpdfdoc/doc_form.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 <vector>
 
 #include "core/fpdfapi/fpdf_font/include/cpdf_fontencoding.h"
 #include "core/fpdfapi/fpdf_page/include/cpdf_page.h"
@@ skipping 325 matching lines @@
   if (!pResDict) {
     return csTmp;
   }
   CPDF_Dictionary* pDict = pResDict->GetDictBy(csType);
   if (!pDict) {
     return csTmp;
   }
   int num = 0;
   CFX_ByteString bsNum;
   while (TRUE) {
-    if (!pDict->KeyExist(csTmp + bsNum)) {
-      return csTmp + bsNum;
+    CFX_ByteString csKey = csTmp + bsNum;
+    if (!pDict->KeyExist(csKey.AsByteStringC())) {
+      return csKey;
     }
     if (m < iCount) {
       csTmp += csStr[m++];
     } else {
       bsNum.Format("%d", num++);
     }
     m++;
   }
   return csTmp;
 }
@@ skipping 842 matching lines @@
     FDF_ImportField(pField, L"", bNotify);
   }
   if (bNotify && m_pFormNotify) {
     m_pFormNotify->AfterFormImportData(this);
   }
   return TRUE;
 }
 void CPDF_InterForm::SetFormNotify(const CPDF_FormNotify* pNotify) {
   m_pFormNotify = (CPDF_FormNotify*)pNotify;
 }