Fix border radius on composited children.

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

Index: third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp
diff --git a/third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp b/third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp
index 7e8e9e6cad804fd0cf1c6dc74cbaaa5830bdfc0a..71f12726b582f92e931df0fdd910f193c9e9894e 100644
--- a/third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp
+++ b/third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp
@@ -201,7 +201,7 @@ CompositedLayerMapping::~CompositedLayerMapping()
         }
     }
 
-    updateClippingLayers(false, false);
+    updateClippingLayers(false, false, false);
     updateOverflowControlsLayers(false, false, false, false);
     updateChildTransformLayer(false);
     updateForegroundLayer(false);
@@ -243,6 +243,7 @@ void CompositedLayerMapping::destroyGraphicsLayers()
         m_graphicsLayer->removeFromParent();
 
     m_ancestorClippingLayer = nullptr;
+    m_ancestorClippingMaskLayer = nullptr;
     m_graphicsLayer = nullptr;
     m_foregroundLayer = nullptr;
     m_backgroundLayer = nullptr;
@@ -414,6 +415,29 @@ bool CompositedLayerMapping::owningLayerClippedByLayerNotAboveCompositedAncestor
     return parentClipRect != LayoutRect::infiniteIntRect();
 }
 
+bool CompositedLayerMapping::owningLayerMaskedByLayerNotAboveCompositedAncestor(const PaintLayer* scrollParent)
+{
+    if (!m_owningLayer.parent())
+        return false;
+
+    const PaintLayer* compositingAncestor = m_owningLayer.enclosingLayerWithCompositedLayerMapping(ExcludeSelf);
+    if (!compositingAncestor)
+        return false;
+
+    const LayoutObject* clippingContainer = m_owningLayer.clippingContainer();
+    if (!clippingContainer)
+        return false;
+
+    if (clippingContainer->enclosingLayer() == scrollParent)
+        return false;
+
+    if (compositingAncestor->layoutObject()->isDescendantOf(clippingContainer))
+        return false;
+
+    DCHECK(clippingContainer->style());
+    return clippingContainer->style()->clipPath() || clippingContainer->style()->hasBorderRadius();
+}
+
 const PaintLayer* CompositedLayerMapping::scrollParent()
 {
     const PaintLayer* scrollParent = m_owningLayer.scrollParent();
@@ -470,8 +494,8 @@ bool CompositedLayerMapping::updateGraphicsLayerConfiguration()
     // clipping layer is necessary to apply the composited clip for this layer.
     bool needsAncestorClip = owningLayerClippedByLayerNotAboveCompositedAncestor(scrollParent)
         && !m_owningLayer.clippingContainer()->enclosingLayer()->hasRootScrollerAsDescendant();
-
-    if (updateClippingLayers(needsAncestorClip, needsDescendantsClippingLayer))
+    bool needsAncestorClippingMask = needsAncestorClip && owningLayerMaskedByLayerNotAboveCompositedAncestor(scrollParent);
+    if (updateClippingLayers(needsAncestorClip, needsAncestorClippingMask, needsDescendantsClippingLayer))
         layerConfigChanged = true;
 
     bool scrollingConfigChanged = false;
@@ -871,6 +895,12 @@ void CompositedLayerMapping::updateAncestorClippingLayerGeometry(const PaintLaye
     // backgroundRect is relative to compositingContainer, so subtract snappedOffsetFromCompositedAncestor.X/snappedOffsetFromCompositedAncestor.Y to get back to local coords.
     m_ancestorClippingLayer->setOffsetFromLayoutObject(parentClipRect.location() - snappedOffsetFromCompositedAncestor);
 
+    if (m_ancestorClippingMaskLayer) {
+        m_ancestorClippingMaskLayer->setPosition(m_ancestorClippingLayer->position()); // TODO(schenney) Don't need this?
+        m_ancestorClippingMaskLayer->setSize(m_ancestorClippingLayer->size());
+        m_ancestorClippingMaskLayer->setNeedsDisplay();
+    }
+
     // The primary layer is then parented in, and positioned relative to this clipping layer.
     graphicsLayerParentLocation = parentClipRect.location();
 }
@@ -1295,6 +1325,9 @@ void CompositedLayerMapping::updateDrawsContent()
     if (m_backgroundLayer)
         m_backgroundLayer->setDrawsContent(hasPaintedContent);
 
+    if (m_ancestorClippingMaskLayer)
+        m_ancestorClippingMaskLayer->setDrawsContent(true);
+
     if (m_maskLayer)
         m_maskLayer->setDrawsContent(true);
 
@@ -1313,18 +1346,32 @@ void CompositedLayerMapping::updateChildrenTransform()
 }
 
 // Return true if the layers changed.
-bool CompositedLayerMapping::updateClippingLayers(bool needsAncestorClip, bool needsDescendantClip)
+bool CompositedLayerMapping::updateClippingLayers(
+    bool needsAncestorClip,
+    bool needsAncestorClippingMask,
+    bool needsDescendantClip)
 {
     bool layersChanged = false;
 
+    // TODO(schenney) correctly handle change to border radius while still needing ancestor clip
     if (needsAncestorClip) {
         if (!m_ancestorClippingLayer) {
             m_ancestorClippingLayer = createGraphicsLayer(CompositingReasonLayerForAncestorClip);
             m_ancestorClippingLayer->setMasksToBounds(true);
             m_ancestorClippingLayer->setShouldFlattenTransform(false);
+            if (needsAncestorClippingMask) {
+                m_ancestorClippingMaskLayer =
+                    createGraphicsLayer(CompositingReasonLayerForAncestorClippingMask);
+                m_ancestorClippingMaskLayer->setPaintingPhase(GraphicsLayerPaintAncestorClippingMask);
+                m_ancestorClippingLayer->setMaskLayer(m_ancestorClippingMaskLayer.get());
+            }
             layersChanged = true;
         }
     } else if (m_ancestorClippingLayer) {
+        if (m_ancestorClippingMaskLayer) {
+            m_ancestorClippingMaskLayer->removeFromParent();
+            m_ancestorClippingMaskLayer = nullptr;
+        }
         m_ancestorClippingLayer->removeFromParent();
         m_ancestorClippingLayer = nullptr;
         layersChanged = true;
@@ -2477,6 +2524,8 @@ void CompositedLayerMapping::paintContents(const GraphicsLayer* graphicsLayer, G
         paintLayerFlags |= PaintLayerPaintingCompositingMaskPhase;
     if (graphicsLayerPaintingPhase & GraphicsLayerPaintChildClippingMask)
         paintLayerFlags |= PaintLayerPaintingChildClippingMaskPhase;
+    if (graphicsLayerPaintingPhase & GraphicsLayerPaintAncestorClippingMask)
+        paintLayerFlags |= PaintLayerPaintingAncestorClippingMaskPhase;
     if (graphicsLayerPaintingPhase & GraphicsLayerPaintOverflowContents)
         paintLayerFlags |= PaintLayerPaintingOverflowContents;
     if (graphicsLayerPaintingPhase & GraphicsLayerPaintCompositedScroll)
@@ -2492,7 +2541,8 @@ void CompositedLayerMapping::paintContents(const GraphicsLayer* graphicsLayer, G
         || graphicsLayer == m_backgroundLayer.get()
         || graphicsLayer == m_maskLayer.get()
         || graphicsLayer == m_childClippingMaskLayer.get()
-        || graphicsLayer == m_scrollingContentsLayer.get()) {
+        || graphicsLayer == m_scrollingContentsLayer.get()
+        || graphicsLayer == m_ancestorClippingMaskLayer.get()) {
 
         bool paintRootBackgroundOntoScrollingContentsLayer = m_backgroundPaintsOntoScrollingContentsLayer;
         DCHECK(!paintRootBackgroundOntoScrollingContentsLayer || (!m_backgroundLayer && !m_foregroundLayer));
@@ -2687,6 +2737,8 @@ String CompositedLayerMapping::debugName(const GraphicsLayer* graphicsLayer) con
         name = "Squashing Layer (first squashed layer: " + (m_squashedLayers.size() > 0 ? m_squashedLayers[0].paintLayer->debugName() : "") + ")";
     } else if (graphicsLayer == m_ancestorClippingLayer.get()) {
         name = "Ancestor Clipping Layer";
+    } else if (graphicsLayer == m_ancestorClippingMaskLayer.get()) {
+        name = "Ancestor Clipping Mask Layer";
     } else if (graphicsLayer == m_foregroundLayer.get()) {
         name = m_owningLayer.debugName() + " (foreground) Layer";
     } else if (graphicsLayer == m_backgroundLayer.get()) {