add Tickmarks to aura overlay scrollbar

third_party/WebKit/Source/platform/scroll/ScrollbarThemeMac.h

Index: third_party/WebKit/Source/platform/scroll/ScrollbarThemeMac.h
diff --git a/third_party/WebKit/Source/platform/scroll/ScrollbarThemeMac.h b/third_party/WebKit/Source/platform/scroll/ScrollbarThemeMac.h
index 069d18ecf881d43164dcd48ad2cb8e0209f5b024..35753a9865532d8ba32a6eb86aee21297e2a0ca4 100644
--- a/third_party/WebKit/Source/platform/scroll/ScrollbarThemeMac.h
+++ b/third_party/WebKit/Source/platform/scroll/ScrollbarThemeMac.h
@@ -90,11 +90,6 @@ class PLATFORM_EXPORT ScrollbarThemeMac : public ScrollbarTheme {
 
   virtual void updateButtonPlacement(WebScrollbarButtonsPlacement) {}
 
-  void paintGivenTickmarks(SkCanvas*,
-                           const Scrollbar&,
-                           const IntRect&,
-                           const Vector<IntRect>&);
-
   IntRect trackRect(const ScrollbarThemeClient&,
                     bool painting = false) override;
   IntRect backButtonRect(const ScrollbarThemeClient&,
@@ -109,6 +104,8 @@ class PLATFORM_EXPORT ScrollbarThemeMac : public ScrollbarTheme {
 
   int minimumThumbLength(const ScrollbarThemeClient&) override;
 
+  int tickmarkBorderWidth() override { return 1; }
+
   RefPtr<Pattern> m_overhangPattern;
 };
 }