Expand PaintLayer clip to account for hidden URL bar with document.rootScroller

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

Index: third_party/WebKit/Source/core/paint/PaintLayerScrollableArea.cpp
diff --git a/third_party/WebKit/Source/core/paint/PaintLayerScrollableArea.cpp b/third_party/WebKit/Source/core/paint/PaintLayerScrollableArea.cpp
index d2c84bbc433e9098dddcd9f950068771ade68037..410132823d99d3cd6ffa74da4ca4096253dbe013 100644
--- a/third_party/WebKit/Source/core/paint/PaintLayerScrollableArea.cpp
+++ b/third_party/WebKit/Source/core/paint/PaintLayerScrollableArea.cpp
@@ -517,7 +517,7 @@ IntSize PaintLayerScrollableArea::maximumScrollOffsetInt() const {
   // than it's overflow clipping box. This is to ensure that content exposed by
   // hiding the URL bar at the bottom of the screen is visible.
   if (this == controller.rootScrollerArea())
-    visibleSize = controller.rootScrollerVisibleArea();
+    visibleSize = controller.visibleContentRect(ExcludeScrollbars).size();
 
   // TODO(skobes): We should really ASSERT that contentSize >= visibleSize
   // when we are not the root layer, but we can't because contentSize is