Fix border radius on composited children.

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

Index: third_party/WebKit/Source/core/paint/PaintLayerClipper.cpp
diff --git a/third_party/WebKit/Source/core/paint/PaintLayerClipper.cpp b/third_party/WebKit/Source/core/paint/PaintLayerClipper.cpp
index 1a7b0d47a54ab09c57564cb94854127dc27d0ffb..7bad7c304f7576fa9303c8fcc913419acb64b943 100644
--- a/third_party/WebKit/Source/core/paint/PaintLayerClipper.cpp
+++ b/third_party/WebKit/Source/core/paint/PaintLayerClipper.cpp
@@ -314,11 +314,29 @@ void PaintLayerClipper::calculateRects(
     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;
   }
 
@@ -343,11 +361,12 @@ void PaintLayerClipper::calculateRects(
   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