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

1 files changed, 1 insertions, 2 deletions

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();