Fix border radius on composited children.

third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.h

Index: third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.h
diff --git a/third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.h b/third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.h
index 53895c4fdd16476b71ea505f4b83d705bb64bc50..bf1e1178266799924265eaa5aac043a65f725b51 100644
--- a/third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.h
+++ b/third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.h
@@ -265,7 +265,7 @@ private:
 
     void updateInternalHierarchy();
     void updatePaintingPhases();
-    bool updateClippingLayers(bool needsAncestorClip, bool needsDescendantClip);
+    bool updateClippingLayers(bool needsAncestorClip, bool needsAncestorClippingMask, bool needsDescendantClip);
     bool updateChildTransformLayer(bool needsChildTransformLayer);
     bool updateOverflowControlsLayers(bool needsHorizontalScrollbarLayer, bool needsVerticalScrollbarLayer, bool needsScrollCornerLayer, bool needsAncestorClip);
     bool updateForegroundLayer(bool needsForegroundLayer);
@@ -330,6 +330,10 @@ private:
     // Return true if |m_owningLayer|'s compositing ancestor is not a descendant (inclusive) of the
     // clipping container for |m_owningLayer|.
     bool owningLayerClippedByLayerNotAboveCompositedAncestor(const PaintLayer* scrollParent);
+    // Return true if |m_owningLayer|'s compositing ancestor is not a descendant (inclusive) of the
+    // clipping container for |m_owningLayer| and that clipping container has border radius.
+    bool owningLayerMaskedByLayerNotAboveCompositedAncestor(const PaintLayer* scrollParent);
+
 
     const PaintLayer* scrollParent();
 
@@ -373,6 +377,7 @@ private:
     // So we create an ancestor clipping layer for B, [+], which ensures that B is clipped
     // as if it had been A's descendant.
     std::unique_ptr<GraphicsLayer> m_ancestorClippingLayer; // Only used if we are clipped by an ancestor which is not a stacking context.
+    std::unique_ptr<GraphicsLayer> m_ancestorClippingMaskLayer; // Only used is there is an m_ancestorClippingLayer that also needs to apply a border radius mask.
     std::unique_ptr<GraphicsLayer> m_graphicsLayer;
     std::unique_ptr<GraphicsLayer> m_childContainmentLayer; // Only used if we have clipping on a stacking context with compositing children.
     std::unique_ptr<GraphicsLayer> m_childTransformLayer; // Only used if we have perspective.