Stop converting widestring -> c_str -> widestring in several places.

fpdfsdk/formfiller/cffl_listbox.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 "fpdfsdk/formfiller/cffl_listbox.h"
 
 #include "fpdfsdk/formfiller/cba_fontmap.h"
 #include "fpdfsdk/formfiller/cffl_formfiller.h"
@@ skipping 34 matching lines @@
 CPWL_Wnd* CFFL_ListBox::NewPDFWindow(const PWL_CREATEPARAM& cp,
                                      CPDFSDK_PageView* pPageView) {
   CPWL_ListBox* pWnd = new CPWL_ListBox();
   pWnd->AttachFFLData(this);
   pWnd->Create(cp);
 
   CFFL_IFormFiller* pIFormFiller = m_pApp->GetIFormFiller();
   pWnd->SetFillerNotify(pIFormFiller);
 
   for (int32_t i = 0, sz = m_pWidget->CountOptions(); i < sz; i++)
-    pWnd->AddString(m_pWidget->GetOptionLabel(i).c_str());
+    pWnd->AddString(m_pWidget->GetOptionLabel(i));
 
   if (pWnd->HasFlag(PLBS_MULTIPLESEL)) {
     m_OriginSelections.clear();
 
     FX_BOOL bSetCaret = FALSE;
     for (int32_t i = 0, sz = m_pWidget->CountOptions(); i < sz; i++) {
       if (m_pWidget->IsOptionSelected(i)) {
         if (!bSetCaret) {
           pWnd->SetCaret(i);
           bSetCaret = TRUE;
@@ skipping 132 matching lines @@
     RestoreState(pPageView);
     pRet = GetPDFWindow(pPageView, FALSE);
   } else {
     pRet = GetPDFWindow(pPageView, TRUE);
   }
 
   m_pWidget->UpdateField();
 
   return pRet;
 }