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

fpdfsdk/pdfwindow/PWL_Edit.h

 // 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
 
 #ifndef FPDFSDK_PDFWINDOW_PWL_EDIT_H_
 #define FPDFSDK_PDFWINDOW_PWL_EDIT_H_
 
 #include "core/fxcrt/include/fx_basic.h"
@@ skipping 67 matching lines @@
 
   void SetCharSpace(FX_FLOAT fCharSpace);
 
   FX_BOOL CanSelectAll() const;
   FX_BOOL CanClear() const;
   FX_BOOL CanCopy() const;
   FX_BOOL CanCut() const;
 
   void CutText();
 
-  void SetText(const FX_WCHAR* csText);
-  void ReplaceSel(const FX_WCHAR* csText);
+  void SetText(const CFX_WideString& csText);
+  void ReplaceSel(const CFX_WideString& csText);
 
   CFX_ByteString GetTextAppearanceStream(const CFX_FloatPoint& ptOffset) const;
   CFX_ByteString GetCaretAppearanceStream(const CFX_FloatPoint& ptOffset) const;
   CFX_ByteString GetSelectAppearanceStream(
       const CFX_FloatPoint& ptOffset) const;
 
   FX_BOOL IsTextFull() const;
 
   static FX_FLOAT GetCharArrayAutoFontSize(CPDF_Font* pFont,
                                            const CFX_FloatRect& rcPlate,
@@ skipping 39 matching lines @@
   CPVT_WordRange GetSameWordsRange(const CPVT_WordPlace& place,
                                    FX_BOOL bLatin,
                                    FX_BOOL bArabic) const;
   IPWL_Filler_Notify* m_pFillerNotify;
   FX_BOOL m_bFocus;
   CFX_FloatRect m_rcOldWindow;
   void* m_pFormFiller;
 };
 
 #endif  // FPDFSDK_PDFWINDOW_PWL_EDIT_H_