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

Source/platform/graphics/paint/DrawingDisplayItem.h

Index: Source/platform/graphics/paint/DrawingDisplayItem.h
diff --git a/Source/platform/graphics/paint/DrawingDisplayItem.h b/Source/platform/graphics/paint/DrawingDisplayItem.h
index 0432462b0d0d1a1616d11b7b9875cec9355be3f1..f6fb613d93a0f0ac0f1c8642537748d5193da82a 100644
--- a/Source/platform/graphics/paint/DrawingDisplayItem.h
+++ b/Source/platform/graphics/paint/DrawingDisplayItem.h
@@ -39,8 +39,8 @@ public:
     }
 
     virtual void replay(GraphicsContext&);
-    virtual void appendToWebDisplayItemList(WebDisplayItemList*) const override;
-    virtual bool drawsContent() const override;
+    void appendToWebDisplayItemList(WebDisplayItemList*) const override;
+    bool drawsContent() const override;
 
     const SkPicture* picture() const { return m_picture.get(); }
 
@@ -50,7 +50,7 @@ public:
 
 private:
 #ifndef NDEBUG
-    virtual void dumpPropertiesAsDebugString(WTF::StringBuilder&) const override;
+    void dumpPropertiesAsDebugString(WTF::StringBuilder&) const override;
 #endif
 
     RefPtr<const SkPicture> m_picture;