Implement overlay scrollbar fade out for non-composited scrollers.

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 b60cfbcbfbea6ef5c5a60358ba6299897314ea72..daa45d18e5079ee58f9fd09953da6acdd9416a61 100644
--- a/third_party/WebKit/Source/platform/scroll/ScrollbarThemeOverlay.cpp
+++ b/third_party/WebKit/Source/platform/scroll/ScrollbarThemeOverlay.cpp
@@ -167,6 +167,9 @@ void ScrollbarThemeOverlay::paintThumb(GraphicsContext& context,
       static_cast<WebScrollbarOverlayColorTheme>(
           scrollbar.getScrollbarOverlayColorTheme());
 
+  if (!scrollbar.enabled())

[skobes, 2016/11/02 21:02:43]

Move this up next to the rest of the "state = " logic.

[bokan, 2016/11/02 22:41:57]

Done.

+    state = WebThemeEngine::StateDisabled;
+
   Platform::current()->themeEngine()->paint(canvas, part, state, WebRect(rect),
                                             &params);
 }
@@ -177,7 +180,11 @@ ScrollbarPart ScrollbarThemeOverlay::hitTest(
   if (m_allowHitTest == DisallowHitTest)
     return NoPart;
 
-  return ScrollbarTheme::hitTest(scrollbar, position);
+  ScrollbarPart part = ScrollbarTheme::hitTest(scrollbar, position);
+  if (part != ThumbPart)
+    return NoPart;
+
+  return ThumbPart;
 }
 
 ScrollbarThemeOverlay& ScrollbarThemeOverlay::mobileTheme() {