Conditionally create PaintLayer's scrollable area object

third_party/WebKit/Source/core/layout/LayoutView.cpp

Index: third_party/WebKit/Source/core/layout/LayoutView.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutView.cpp b/third_party/WebKit/Source/core/layout/LayoutView.cpp
index bbfcf0dd2f7f72df06cf0b364b4a488ec092fca9..ddce6d9498fb20e3fbc3150606245ff0b66571c7 100644
--- a/third_party/WebKit/Source/core/layout/LayoutView.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutView.cpp
@@ -1003,4 +1003,18 @@ void LayoutView::sendMediaPositionChangeNotifications(const IntRect& visibleRect
     }
 }
 
+void LayoutView::updateFromStyle()
+{
+    LayoutBlockFlow::updateFromStyle();
+
+    // LayoutView of the main frame is responsible for painting base background.
+    if (!document().ownerElement())
+        setHasBoxDecorationBackground(true);
+}
+
+bool LayoutView::allowsOverflowClip() const
+{
+    return document().settings() && document().settings()->rootLayerScrolls();
+}
+
 } // namespace blink