Implement overlay scrollbar fade out for non-composited scrollers.

third_party/WebKit/Source/core/paint/PaintLayerScrollableArea.h

Index: third_party/WebKit/Source/core/paint/PaintLayerScrollableArea.h
diff --git a/third_party/WebKit/Source/core/paint/PaintLayerScrollableArea.h b/third_party/WebKit/Source/core/paint/PaintLayerScrollableArea.h
index 8abad8fe52d6c852b72a69322411356155d37cea..c05ea0ef5a02e046f53c4331076f2b5cabab8628 100644
--- a/third_party/WebKit/Source/core/paint/PaintLayerScrollableArea.h
+++ b/third_party/WebKit/Source/core/paint/PaintLayerScrollableArea.h
@@ -295,6 +295,8 @@ class CORE_EXPORT PaintLayerScrollableArea final
   ScrollBehavior scrollBehaviorStyle() const override;
   CompositorAnimationTimeline* compositorAnimationTimeline() const override;
 
+  void visibleContentResized();

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

"visibleSizeChanged" might be clearer.

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

Thanks, done.

+
   // FIXME: We shouldn't allow access to m_overflowRect outside this class.
   LayoutRect overflowRect() const { return m_overflowRect; }
 
@@ -321,8 +323,6 @@ class CORE_EXPORT PaintLayerScrollableArea final
   void updateAfterLayout();
   void clampScrollOffsetsAfterLayout();
 
-  void didChangeScrollbarsHidden() override;
-
   void updateAfterStyleChange(const ComputedStyle*);
   void updateAfterOverflowRecalc();