Fix -Wnon-virtual-dtor compiler warnings.

core/include/fpdfapi/fpdf_parser.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 _FPDF_PARSER_
 #define _FPDF_PARSER_
 #ifndef _FX_BASIC_H_
 #include "../fxcrt/fx_ext.h"
@@ skipping 31 matching lines @@
 #define FPDFPERM_EXTRACT                0x0010
 #define FPDFPERM_ANNOT_FORM             0x0020
 #define FPDFPERM_FILL_FORM              0x0100
 #define FPDFPERM_EXTRACT_ACCESS 0x0200
 #define FPDFPERM_ASSEMBLE               0x0400
 #define FPDFPERM_PRINT_HIGH             0x0800
 #define FPDF_PAGE_MAX_NUM               0xFFFFF
 class IPDF_EnumPageHandler
 {
 public:
-
+    virtual ~IPDF_EnumPageHandler() { }
     virtual FX_BOOL EnumPage(CPDF_Dictionary* pPageDict) = 0;
 };
 class CPDF_Document : public CFX_PrivateData, public CPDF_IndirectObjects
 {
 public:
 
     CPDF_Document(IPDF_DocParser* pParser);
 
     CPDF_Document();
 
@@ skipping 177 matching lines @@
 
     FX_DWORD                    m_dwSize;
 
     FX_DWORD                    m_dwCurPos;
 };
 class CPDF_SyntaxParser : public CFX_Object
 {
 public:
 
     CPDF_SyntaxParser();
-
-    ~CPDF_SyntaxParser();
+    virtual ~CPDF_SyntaxParser();
 
     void                                InitParser(IFX_FileRead* pFileAccess, FX_DWORD HeaderOffset);
 
     FX_FILESIZE                 SavePos()
     {
         return m_Pos;
     }
 
     void                                RestorePos(FX_FILESIZE pos)
     {
@@ skipping 97 matching lines @@
 
     FX_FILESIZE m_DictEnd;
 
     FX_FILESIZE m_DataStart;
 
     FX_FILESIZE m_DataEnd;
 };
 class IPDF_DocParser : public CFX_Object
 {
 public:
-
+    virtual ~IPDF_DocParser() { }
     virtual FX_DWORD    GetRootObjNum() = 0;
 
     virtual FX_DWORD    GetInfoObjNum() = 0;
 
     virtual CPDF_Object*        ParseIndirectObject(CPDF_IndirectObjects* pObjList, FX_DWORD objnum, PARSE_CONTEXT* pContext = NULL) = 0;
 
     virtual FX_DWORD    GetLastObjNum() = 0;
 
     virtual CPDF_Array* GetIDArray() = 0;
 
@@ skipping 15 matching lines @@
 #define PDFPARSE_ERROR_FILE                     1
 #define PDFPARSE_ERROR_FORMAT           2
 #define PDFPARSE_ERROR_PASSWORD         3
 #define PDFPARSE_ERROR_HANDLER          4
 #define PDFPARSE_ERROR_CERT                     5
 class CPDF_Parser FX_FINAL : public IPDF_DocParser
 {
 public:
 
     CPDF_Parser();
-
-    ~CPDF_Parser();
+    ~CPDF_Parser() override;
 
     FX_DWORD                    StartParse(FX_LPCSTR filename, FX_BOOL bReParse = FALSE);
 
     FX_DWORD                    StartParse(FX_LPCWSTR filename, FX_BOOL bReParse = FALSE);
 
     FX_DWORD                    StartParse(IFX_FileRead* pFile, FX_BOOL bReParse = FALSE, FX_BOOL bOwnFileRead = TRUE);
 
     void                                CloseParser(FX_BOOL bReParse = FALSE);
 
     virtual FX_DWORD    GetPermissions(FX_BOOL bCheckRevision = FALSE) FX_OVERRIDE;
@@ skipping 429 matching lines @@
 
     CPDF_Object*                LookupValue(int num);
 protected:
 
     CPDF_Dictionary*    m_pRoot;
 };
 
 class IFX_FileAvail
 {
 public:
-
+    virtual ~IFX_FileAvail() { }
     virtual FX_BOOL                     IsDataAvail( FX_FILESIZE offset, FX_DWORD size) = 0;
 };
 class IFX_DownloadHints
 {
 public:
-
+    virtual ~IFX_DownloadHints() { }
     virtual void                        AddSegment(FX_FILESIZE offset, FX_DWORD size) = 0;
 };
 #define PDF_IS_LINEARIZED                       1
 #define PDF_NOT_LINEARIZED                      0
 #define PDF_UNKNOW_LINEARIZED           -1
 #define PDFFORM_NOTAVAIL                0
 #define PDFFORM_AVAIL                   1
 #define PDFFORM_NOTEXIST                2
 class IPDF_DataAvail
 {
 public:
+    virtual ~IPDF_DataAvail() { }
 
     virtual FX_BOOL                     IsDocAvail(IFX_DownloadHints* pHints) = 0;
 
-
     virtual void                        SetDocument(CPDF_Document* pDoc) = 0;
 
-
     virtual FX_BOOL                     IsPageAvail(int iPage, IFX_DownloadHints* pHints) = 0;
 
     virtual FX_BOOL                     IsLinearized() = 0;
 
     virtual FX_INT32            IsFormAvail(IFX_DownloadHints *pHints) = 0;
 
     virtual FX_INT32            IsLinearizedPDF() = 0;
 
     virtual void                                GetLinearizedMainXRefInfo(FX_FILESIZE *pPos, FX_DWORD *pSize) = 0;
 };
@@ skipping 247 matching lines @@
 
     FX_BOOL                             m_bCurPageDictLoadOK;
 
     CPDF_PageNode                       m_pageNodes;
 
     CFX_CMapDWordToDWord *              m_pageMapCheckState;
 
     CFX_CMapDWordToDWord *              m_pagesLoadState;
 };
 #endif