add Tickmarks to aura overlay scrollbar

third_party/WebKit/Source/platform/scroll/ScrollbarThemeOverlay.cpp

Index: third_party/WebKit/Source/platform/scroll/ScrollbarThemeOverlay.cpp
diff --git a/third_party/WebKit/Source/platform/scroll/ScrollbarThemeOverlay.cpp b/third_party/WebKit/Source/platform/scroll/ScrollbarThemeOverlay.cpp
index 9b1fb69267c52a13da0f04d73048b7b99bf13afe..79488a96fe74d7c13a5cffd788007493adcb2921 100644
--- a/third_party/WebKit/Source/platform/scroll/ScrollbarThemeOverlay.cpp
+++ b/third_party/WebKit/Source/platform/scroll/ScrollbarThemeOverlay.cpp
@@ -29,6 +29,7 @@
 #include "platform/graphics/GraphicsContext.h"
 #include "platform/graphics/paint/DrawingRecorder.h"
 #include "platform/scroll/Scrollbar.h"
+#include "platform/scroll/ScrollbarThemeAura.h"
 #include "platform/transforms/TransformationMatrix.h"
 #include "public/platform/Platform.h"
 #include "public/platform/WebRect.h"
@@ -134,6 +135,12 @@ IntRect ScrollbarThemeOverlay::trackRect(const ScrollbarThemeClient& scrollbar,
   return rect;
 }
 
+void ScrollbarThemeOverlay::paintTickmarks(GraphicsContext& context,
+                                           const Scrollbar& scrollbar,
+                                           const IntRect& rect) {
+  ScrollbarThemeAura::paintAuraTickmarks(context, scrollbar, rect);
+}
+
 int ScrollbarThemeOverlay::thumbThickness(const ScrollbarThemeClient&) {
   return m_thumbThickness;
 }