Make down-conversion explicit from CFX_Widetring to CFX_WideStringC.

xfa/fxfa/app/xfa_textlayout.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 XFA_FXFA_APP_XFA_TEXTLAYOUT_H_
 #define XFA_FXFA_APP_XFA_TEXTLAYOUT_H_
 
 #include "xfa/fde/css/fde_css.h"
 #include "xfa/fde/fde_brush.h"
 #include "xfa/fde/fde_renderdevice.h"
 #include "xfa/fgas/layout/fgas_rtfbreak.h"
 #include "xfa/fxfa/parser/xfa_object.h"
 #include "xfa/include/fxfa/xfa_ffdoc.h"
 
 #define XFA_LOADERCNTXTFLG_FILTERSPACE 0x001
 
 class CXFA_Para;
 class CXFA_Font;
 class CXFA_TextProvider;
 class CXFA_TextTabstopsContext;
 
 class CXFA_CSSTagProvider : public IFDE_CSSTagProvider {
  public:
   CXFA_CSSTagProvider() : m_bTagAviliable(FALSE), m_bContent(FALSE) {}
   virtual ~CXFA_CSSTagProvider();
-  virtual CFX_WideStringC GetTagName() { return m_wsTagName; }
+
+  // Note: |this| must outlive the use of GetTagName()'s result.
+  virtual CFX_WideStringC GetTagName() { return m_wsTagName.AsWideStringC(); }
   virtual FX_POSITION GetFirstAttribute() {
     return m_Attributes.GetStartPosition();
   }
   virtual void GetNextAttribute(FX_POSITION& pos,
                                 CFX_WideStringC& wsAttr,
                                 CFX_WideStringC& wsValue);
   void SetTagNameObj(const CFX_WideString& wsName) { m_wsTagName = wsName; }
   void SetAttribute(const CFX_WideString& wsAttr,
                     const CFX_WideString& wsValue);
   FX_BOOL m_bTagAviliable;
@@ skipping 364 matching lines @@
   CXFA_LoaderContext* m_pLoader;
   int32_t m_iLines;
   FX_FLOAT m_fMaxWidth;
   CXFA_TextParser m_textParser;
   CXFA_PieceLineArray m_pieceLines;
   CXFA_TextTabstopsContext* m_pTabstopContext;
   FX_BOOL m_bBlockContinue;
 };
 
 #endif  // XFA_FXFA_APP_XFA_TEXTLAYOUT_H_