Blink Support for Overlay Scrollbar Animation

Source/platform/scroll/ScrollbarThemeAura.cpp

Index: Source/platform/scroll/ScrollbarThemeAura.cpp
diff --git a/Source/platform/scroll/ScrollbarThemeAura.cpp b/Source/platform/scroll/ScrollbarThemeAura.cpp
index 829242067f241c9e52f35fb048f419f683bfe5ca..f4c9dc0390f522f99a50a66a177fd3712dc1a6a0 100644
--- a/Source/platform/scroll/ScrollbarThemeAura.cpp
+++ b/Source/platform/scroll/ScrollbarThemeAura.cpp
@@ -41,6 +41,12 @@
 #include "public/platform/WebRect.h"
 #include "public/platform/WebThemeEngine.h"
 
+namespace {
+
+const int kDefaultOverlayScrollbarThumbThickness = 13;
+
+} // namespace
+
 namespace blink {
 
 static bool useMockTheme()
@@ -51,7 +57,7 @@ static bool useMockTheme()
 ScrollbarTheme* ScrollbarTheme::nativeTheme()
 {
     if (RuntimeEnabledFeatures::overlayScrollbarsEnabled()) {
-        DEFINE_STATIC_LOCAL(ScrollbarThemeOverlay, theme, (10, 0, ScrollbarThemeOverlay::AllowHitTest));
+        DEFINE_STATIC_LOCAL(ScrollbarThemeOverlay, theme, (kDefaultOverlayScrollbarThumbThickness, 0, ScrollbarThemeOverlay::AllowHitTest));
         return &theme;
     }