Fix virtual/override/final usage in Source/platform/.

Source/platform/graphics/UnacceleratedImageBufferSurface.h

Index: Source/platform/graphics/UnacceleratedImageBufferSurface.h
diff --git a/Source/platform/graphics/UnacceleratedImageBufferSurface.h b/Source/platform/graphics/UnacceleratedImageBufferSurface.h
index 53939615d39f58f32518008ad29002aa4164e9b7..9df62200a3f2d2dd46ac15e216cd22ed152cc855 100644
--- a/Source/platform/graphics/UnacceleratedImageBufferSurface.h
+++ b/Source/platform/graphics/UnacceleratedImageBufferSurface.h
@@ -42,12 +42,12 @@ class PLATFORM_EXPORT UnacceleratedImageBufferSurface : public ImageBufferSurfac
     WTF_MAKE_NONCOPYABLE(UnacceleratedImageBufferSurface); WTF_MAKE_FAST_ALLOCATED(UnacceleratedImageBufferSurface);
 public:
     UnacceleratedImageBufferSurface(const IntSize&, OpacityMode = NonOpaque);
-    virtual ~UnacceleratedImageBufferSurface();
+    ~UnacceleratedImageBufferSurface() override;
 
-    virtual SkCanvas* canvas() const override;
-    virtual bool isValid() const override;
+    SkCanvas* canvas() const override;
+    bool isValid() const override;
 
-    virtual PassRefPtr<SkImage> newImageSnapshot() const override;
+    PassRefPtr<SkImage> newImageSnapshot() const override;
 private:
     RefPtr<SkSurface> m_surface;
 };