Revert of Calculate paint invalidation rect for scrollbars

third_party/WebKit/Source/core/layout/LayoutObject.h

Index: third_party/WebKit/Source/core/layout/LayoutObject.h
diff --git a/third_party/WebKit/Source/core/layout/LayoutObject.h b/third_party/WebKit/Source/core/layout/LayoutObject.h
index 62831dad63597dc6cd2e82180415e0d0da79b81f..6b76d49513b1ab26c8c7a64086aa84878b7d6c7b 100644
--- a/third_party/WebKit/Source/core/layout/LayoutObject.h
+++ b/third_party/WebKit/Source/core/layout/LayoutObject.h
@@ -1300,7 +1300,14 @@
     DisplayItemClient displayItemClient() const { return toDisplayItemClient(this); }
 
     void invalidateDisplayItemClient(const DisplayItemClientWrapper&) const;
-    void invalidateDisplayItemClientsIncludingNonCompositingDescendants(const LayoutBoxModelObject* paintInvalidationContainer, PaintInvalidationReason, const LayoutRect* paintInvalidationRect) const;
+    void invalidateDisplayItemClientForNonCompositingDescendants() const { invalidateDisplayItemClientForNonCompositingDescendantsOf(*this); }
+    // A normal object should use invalidateDisplayItemClientForNonCompositingDescendants()
+    // to invalidate its descendants which are painted on the same backing. However, for
+    // an object (e.g. LayoutScrollbarPart, custom scroll corner, custom resizer) which is
+    // not hooked up in the layout tree and not able to find its paint backing, it should
+    // let its owning layout object call the following function.
+    // FIXME: should we hook up scrollbar parts in the layout tree? crbug.com/484263.
+    void invalidateDisplayItemClientForNonCompositingDescendantsOf(const LayoutObject&) const;
 
     // Called before anonymousChild.setStyle(). Override to set custom styles for the child.
     virtual void updateAnonymousChildStyle(const LayoutObject& anonymousChild, ComputedStyle& style) const { }