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

Source/platform/scroll/ScrollbarThemeMacCommon.h

Index: Source/platform/scroll/ScrollbarThemeMacCommon.h
diff --git a/Source/platform/scroll/ScrollbarThemeMacCommon.h b/Source/platform/scroll/ScrollbarThemeMacCommon.h
index e0c0d03fe83b730b502ab1d35e9cff2e815af12c..c6be4c41b44a58e561fbcc08d7e94509754b1cb7 100644
--- a/Source/platform/scroll/ScrollbarThemeMacCommon.h
+++ b/Source/platform/scroll/ScrollbarThemeMacCommon.h
@@ -37,27 +37,27 @@ class Pattern;
 
 class PLATFORM_EXPORT ScrollbarThemeMacCommon : public ScrollbarTheme {
 public:
-    virtual ~ScrollbarThemeMacCommon();
+    ~ScrollbarThemeMacCommon() override;
 
-    virtual void registerScrollbar(ScrollbarThemeClient*) override;
-    virtual void unregisterScrollbar(ScrollbarThemeClient*) override;
+    void registerScrollbar(ScrollbarThemeClient*) override;
+    void unregisterScrollbar(ScrollbarThemeClient*) override;
     void preferencesChanged(float initialButtonDelay, float autoscrollButtonDelay, NSScrollerStyle preferredScrollerStyle, bool redraw);
 
-    virtual bool supportsControlTints() const override { return true; }
+    bool supportsControlTints() const override { return true; }
 
-    virtual double initialAutoscrollTimerDelay() override;
-    virtual double autoscrollTimerDelay() override;
+    double initialAutoscrollTimerDelay() override;
+    double autoscrollTimerDelay() override;
 
-    virtual void paintTickmarks(GraphicsContext*, ScrollbarThemeClient*, const IntRect&) override;
+    void paintTickmarks(GraphicsContext*, ScrollbarThemeClient*, const IntRect&) override;
 
     static NSScrollerStyle recommendedScrollerStyle();
 
     static bool isOverlayAPIAvailable();
 
 protected:
-    virtual int maxOverlapBetweenPages() override { return 40; }
+    int maxOverlapBetweenPages() override { return 40; }
 
-    virtual bool shouldDragDocumentInsteadOfThumb(ScrollbarThemeClient*, const PlatformMouseEvent&) override;
+    bool shouldDragDocumentInsteadOfThumb(ScrollbarThemeClient*, const PlatformMouseEvent&) override;
     int scrollbarPartToHIPressedState(ScrollbarPart);
 
     virtual void updateButtonPlacement() { }