Aura overlay scrollbars adjust color for dark backgrounds

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

Index: third_party/WebKit/Source/platform/scroll/ScrollbarThemeAura.cpp
diff --git a/third_party/WebKit/Source/platform/scroll/ScrollbarThemeAura.cpp b/third_party/WebKit/Source/platform/scroll/ScrollbarThemeAura.cpp
index 6d213bed316a255435be846e8e016c116a4cfec2..29663ececfe5a08c831d2bf280476b353601a06d 100644
--- a/third_party/WebKit/Source/platform/scroll/ScrollbarThemeAura.cpp
+++ b/third_party/WebKit/Source/platform/scroll/ScrollbarThemeAura.cpp
@@ -340,11 +340,13 @@ void ScrollbarThemeAura::paintThumb(GraphicsContext& gc,
     state = WebThemeEngine::StateHover;
   else
     state = WebThemeEngine::StateNormal;
+
+  blink::WebThemeEngine::ExtraParams params;
   Platform::current()->themeEngine()->paint(
       canvas, scrollbar.orientation() == HorizontalScrollbar
                   ? WebThemeEngine::PartScrollbarHorizontalThumb
                   : WebThemeEngine::PartScrollbarVerticalThumb,
-      state, WebRect(rect), 0);
+      state, WebRect(rect), &params);

[bokan, 2016/10/21 20:11:38]

Ah, this is why you had the |else| case in GetNativeThemeExtraParams, yes? In
that case, this can remain nullptr, just add an early return in
GetNativeThemeExtraParams if WebThemeEngine::ExtraParams is nullptr

 }
 
 bool ScrollbarThemeAura::shouldRepaintAllPartsOnInvalidation() const {