Fix border radius on composited children.

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

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. 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 296 matching lines @@
   CHECK_RECTS_EQ(testLayerBounds, layerBounds);
 #endif
 }
 
 void PaintLayerClipper::calculateRects(
     const ClipRectsContext& context,
     const LayoutRect& paintDirtyRect,
     LayoutRect& layerBounds,
     ClipRect& backgroundRect,
     ClipRect& foregroundRect,
-    const LayoutPoint* offsetFromRoot) const {
+    const LayoutPoint* offsetFromRoot,
+    const bool addAncestorClips) const {
   if (m_geometryMapper) {
     calculateRectsWithGeometryMapper(context, paintDirtyRect, layerBounds,
                                      backgroundRect, foregroundRect,
                                      offsetFromRoot);
+
+    // CSS clip (different than clipping due to overflow) can clip to any box,
+    // even if it falls outside of the border box.

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

Wrong base? I'm not sure I changed this.

+    LayoutBoxModelObject& layoutObject = *m_layer.layoutObject();
+    LayoutPoint offset;
+    if (offsetFromRoot)
+      offset = *offsetFromRoot;
+    else
+      m_layer.convertToLayerCoords(context.rootLayer, offset);
+    if (layoutObject.hasClip()) {
+      // Clip applies to *us* as well, so go ahead and update the damageRect.
+      LayoutRect newPosClip = toLayoutBox(layoutObject).clipRect(offset);
+      backgroundRect.intersect(newPosClip);
+      backgroundRect.setIsClippedByClipCss();
+      foregroundRect.intersect(newPosClip);
+      foregroundRect.setIsClippedByClipCss();
+    }
     return;
   }
 
   bool isClippingRoot = &m_layer == context.rootLayer;
   LayoutBoxModelObject& layoutObject = *m_layer.layoutObject();
 
   if (!isClippingRoot && m_layer.parent()) {
     backgroundRect = backgroundClipRect(context);
     backgroundRect.move(context.subPixelAccumulation);
     backgroundRect.intersect(paintDirtyRect);
   } else {
     backgroundRect = paintDirtyRect;
   }
 
   foregroundRect = backgroundRect;
 
   LayoutPoint offset;
   if (offsetFromRoot)
     offset = *offsetFromRoot;
   else
     m_layer.convertToLayerCoords(context.rootLayer, offset);
   layerBounds = LayoutRect(offset, LayoutSize(m_layer.size()));
 
   // Update the clip rects that will be passed to child layers.
-  if (shouldClipOverflow(context)) {
+  if (addAncestorClips || shouldClipOverflow(context)) {

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

Trying to get rid of this by having the layoutObject be the clipping container.

+    if (addAncestorClips) fprintf(stderr, "Preparing due to addAncestorClips\n");
     foregroundRect.intersect(
         toLayoutBox(layoutObject)
             .overflowClipRect(offset, context.overlayScrollbarClipBehavior));
-    if (layoutObject.styleRef().hasBorderRadius())
+    if (layoutObject.styleRef().hasBorderRadius() || addAncestorClips)
       foregroundRect.setHasRadius(true);
 
     // FIXME: Does not do the right thing with columns yet, since we don't yet
     // factor in the individual column boxes as overflow.
 
     // The LayoutView is special since its overflow clipping rect may be larger
     // than its box rect (crbug.com/492871).
     LayoutRect layerBoundsWithVisualOverflow =
         layoutObject.isLayoutView()
             ? toLayoutView(layoutObject).viewRect()
@@ skipping 190 matching lines @@
     const LayoutSize& subpixelAccumulation) const {
   DCHECK(!m_geometryMapper);
   ClipRectsContext context(rootLayer, PaintingClipRects,
                            IgnoreOverlayScrollbarSize, subpixelAccumulation);
   if (respectOverflowClip == IgnoreOverflowClip)
     context.setIgnoreOverflowClip();
   return getClipRects(context);
 }
 
 }  // namespace blink