Fix -Wnon-virtual-dtor compiler warnings.

This is done by explicitly adding a virtual dtor to interface classes,
since the cost is small given that there are already virtual functions.

The exceptions are for classes that have a Release() or Delete() method,
in which case it is non-virtual and protected to indicate that the virtual
class is never the deletion point.

BUG=
R=brucedawson@chromium.org, thestig@chromium.org

Review URL: https://codereview.chromium.org/810883005

4 files changed, 18 insertions, 4 deletions

diff --git a/core/include/fxge/fpf.h b/core/include/fxge/fpf.h
index 99d9b7c999..28d028cfbb 100644
--- a/core/include/fxge/fpf.h
+++ b/core/include/fxge/fpf.h
@@ -12,6 +12,7 @@ class IFPF_Font;
 class IFPF_DeviceModule
 {
 public:
+    virtual ~IFPF_DeviceModule() { }
     virtual void				Destroy() = 0;
     virtual IFPF_FontMgr*		GetFontMgr() = 0;
 };
@@ -41,10 +42,14 @@ public:
     virtual FX_INT32		GetHeight() const = 0;
     virtual FX_INT32		GetItalicAngle() const = 0;
     virtual FX_DWORD		GetFontData(FX_DWORD dwTable, FX_LPBYTE pBuffer, FX_DWORD dwSize) = 0;
+
+protected:
+    ~IFPF_Font() { }
 };
 class IFPF_FontMgr
 {
 public:
+    virtual ~IFPF_FontMgr() { }
     virtual void			LoadSystemFonts() = 0;
     virtual void			LoadPrivateFont(IFX_FileRead* pFontFile) = 0;
     virtual void			LoadPrivateFont(FX_BSTR bsFileName) = 0;
diff --git a/core/include/fxge/fx_dib.h b/core/include/fxge/fx_dib.h
index d8a2003548..f7e435d966 100644
--- a/core/include/fxge/fx_dib.h
+++ b/core/include/fxge/fx_dib.h
@@ -402,16 +402,15 @@ protected:
 class IFX_ScanlineComposer
 {
 public:
+    virtual ~IFX_ScanlineComposer() { }
 
     virtual	void		ComposeScanline(int line, FX_LPCBYTE scanline, FX_LPCBYTE scan_extra_alpha = NULL) = 0;
 
-
     virtual FX_BOOL		SetInfo(int width, int height, FXDIB_Format src_format, FX_DWORD* pSrcPalette) = 0;
 };
 class CFX_ScanlineCompositor : public CFX_Object
 {
 public:
-
     CFX_ScanlineCompositor();
 
     ~CFX_ScanlineCompositor();
diff --git a/core/include/fxge/fx_font.h b/core/include/fxge/fx_font.h
index 52f8f30d8d..bf9bb40500 100644
--- a/core/include/fxge/fx_font.h
+++ b/core/include/fxge/fx_font.h
@@ -243,6 +243,7 @@ public:
 class IFX_FontEnumerator
 {
 public:
+    virtual ~IFX_FontEnumerator() { }
 
     virtual void		HitFont() = 0;
 
@@ -251,6 +252,7 @@ public:
 class IFX_AdditionalFontEnum
 {
 public:
+    virtual ~IFX_AdditionalFontEnum() { }
     virtual int  CountFiles() = 0;
     virtual IFX_FileStream* GetFontFile(int index) = 0;
 };
@@ -296,6 +298,7 @@ class IFX_SystemFontInfo : public CFX_Object
 public:
     static IFX_SystemFontInfo*	CreateDefault();
     virtual void		Release() = 0;
+
     virtual	FX_BOOL		EnumFontList(CFX_FontMapper* pMapper) = 0;
     virtual void*		MapFont(int weight, FX_BOOL bItalic, int charset, int pitch_family, FX_LPCSTR face, FX_BOOL& bExact) = 0;
     virtual void*		GetFont(FX_LPCSTR face) = 0;
@@ -311,6 +314,8 @@ public:
     {
         return NULL;
     }
+protected:
+    ~IFX_SystemFontInfo() { }
 };
 class CFX_FolderFontInfo : public IFX_SystemFontInfo
 {
@@ -423,6 +428,9 @@ class IFX_GSUBTable
 public:
     virtual void	Release() = 0;
     virtual FX_BOOL GetVerticalGlyph(FX_DWORD glyphnum, FX_DWORD* vglyphnum) = 0;
+
+protected:
+     ~IFX_GSUBTable() { }
 };
 IFX_GSUBTable* FXGE_CreateGSUBTable(CFX_Font* pFont);
 #endif
diff --git a/core/include/fxge/fx_ge.h b/core/include/fxge/fx_ge.h
index 82719ffda6..0c4bce8003 100644
--- a/core/include/fxge/fx_ge.h
+++ b/core/include/fxge/fx_ge.h
@@ -637,9 +637,11 @@ public:
 class IFX_PSOutput
 {
 public:
-
-    virtual void	OutputPS(FX_LPCSTR string, int len) = 0;
     virtual void  Release() = 0;
+    virtual void	OutputPS(FX_LPCSTR string, int len) = 0;
+
+protected:
+    ~IFX_PSOutput() { }
 };
 class CPSFont;
 class CFX_PSRenderer : public CFX_Object