Fix border radius on composited children.

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

 /*
  * Copyright (C) 2003, 2009, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Intel Corporation. All rights reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@web.de>
@@ skipping 817 matching lines @@
 
   bool hasSelfPaintingLayerDescendant() const {
     if (m_hasSelfPaintingLayerDescendantDirty)
       updateHasSelfPaintingLayerDescendant();
     DCHECK(!m_hasSelfPaintingLayerDescendantDirty);
     return m_hasSelfPaintingLayerDescendant;
   }
   LayoutRect paintingExtent(const PaintLayer* rootLayer,
                             const LayoutSize& subPixelAccumulation,
                             GlobalPaintFlags);
+
   void appendSingleFragmentIgnoringPagination(
       PaintLayerFragments&,
       const PaintLayer* rootLayer,
       const LayoutRect& dirtyRect,
       ClipRectsCacheSlot,
       OverlayScrollbarClipBehavior = IgnoreOverlayScrollbarSize,
       ShouldRespectOverflowClipType = RespectOverflowClip,
+      bool paintingAncestorClippingMask = false,

[Stephen Chennney, 2016/11/08 21:42:52]

I'm trying to get rid of this extra arg. It's hackish.

       const LayoutPoint* offsetFromRoot = 0,
       const LayoutSize& subPixelAccumulation = LayoutSize());
   void collectFragments(
       PaintLayerFragments&,
       const PaintLayer* rootLayer,
       const LayoutRect& dirtyRect,
       ClipRectsCacheSlot,
       OverlayScrollbarClipBehavior = IgnoreOverlayScrollbarSize,
       ShouldRespectOverflowClipType = RespectOverflowClip,
+      bool paintingAncestorClippingMask = false,
       const LayoutPoint* offsetFromRoot = 0,
       const LayoutSize& subPixelAccumulation = LayoutSize(),
       const LayoutRect* layerBoundingBox = 0);
 
   LayoutPoint layoutBoxLocation() const {
     return layoutObject()->isBox() ? toLayoutBox(layoutObject())->location()
                                    : LayoutPoint();
   }
 
   enum TransparencyClipBoxBehavior {
@@ skipping 357 matching lines @@
 
 }  // namespace blink
 
 #ifndef NDEBUG
 // Outside the WebCore namespace for ease of invocation from gdb.
 CORE_EXPORT void showLayerTree(const blink::PaintLayer*);
 CORE_EXPORT void showLayerTree(const blink::LayoutObject*);
 #endif
 
 #endif  // Layer_h