Make CFX_WideString(const CFX_WideString&) explicit.

xfa/fgas/localization/fgas_localemgr.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_FGAS_LOCALIZATION_FGAS_LOCALEMGR_H_
 #define XFA_FGAS_LOCALIZATION_FGAS_LOCALEMGR_H_
 
 #include "xfa/fgas/localization/fgas_locale.h"
 
 class CFX_LocaleMgr : public IFX_LocaleMgr {
  public:
   CFX_LocaleMgr(uint16_t wDefLCID);
-  virtual void Release() { delete this; }
-  virtual uint16_t GetDefLocaleID();
-  virtual IFX_Locale* GetDefLocale();
-  virtual IFX_Locale* GetLocale(uint16_t lcid);
-  virtual IFX_Locale* GetLocaleByName(const CFX_WideStringC& wsLocaleName);
+
+  void Release() override { delete this; }
+  uint16_t GetDefLocaleID() override;
+  IFX_Locale* GetDefLocale() override;
+  IFX_Locale* GetLocale(uint16_t lcid) override;
+  IFX_Locale* GetLocaleByName(const CFX_WideString& wsLocaleName) override;
+
   CFX_MapPtrToPtr m_lcid2xml;
 
  protected:
-  ~CFX_LocaleMgr();
+  ~CFX_LocaleMgr() override;
   CFX_MapPtrToPtr m_lcid2locale;
   uint16_t m_wDefLCID;
 };
 
 #endif  // XFA_FGAS_LOCALIZATION_FGAS_LOCALEMGR_H_