Make code compile with clang_use_chrome_plugin (final)

xfa/fde/css/fde_csssyntax.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_FDE_CSS_FDE_CSSSYNTAX_H_
 #define XFA_FDE_CSS_FDE_CSSSYNTAX_H_
 
 #include "xfa/fde/css/fde_css.h"
 #include "xfa/fgas/crt/fgas_memory.h"
 #include "xfa/fgas/crt/fgas_stream.h"
 
 class CFDE_CSSTextBuf : public CFX_Target {
  public:
   CFDE_CSSTextBuf();
-  ~CFDE_CSSTextBuf();
+  ~CFDE_CSSTextBuf() override;
+
   FX_BOOL AttachBuffer(const FX_WCHAR* pBuffer, int32_t iBufLen);
   FX_BOOL EstimateSize(int32_t iAllocSize);
   int32_t LoadFromStream(IFX_Stream* pTxtStream,
                          int32_t iStreamOffset,
                          int32_t iMaxChars,
                          FX_BOOL& bEOS);
   FX_BOOL AppendChar(FX_WCHAR wch) {
     if (m_iDatLen >= m_iBufLen && !ExpandBuf(m_iBufLen * 2)) {
       return FALSE;
     }
@@ skipping 83 matching lines @@
   CFDE_CSSTextBuf m_TextData;
   CFDE_CSSTextBuf m_TextPlane;
   int32_t m_iTextDatLen;
   uint32_t m_dwCheck;
   FDE_CSSSYNTAXMODE m_eMode;
   FDE_CSSSYNTAXSTATUS m_eStatus;
   CFX_StackTemplate<FDE_CSSSYNTAXMODE> m_ModeStack;
 };
 
 #endif  // XFA_FDE_CSS_FDE_CSSSYNTAX_H_