Large canvas does not honor containing div's border radius

Source/core/rendering/RenderLayer.cpp

Index: Source/core/rendering/RenderLayer.cpp
diff --git a/Source/core/rendering/RenderLayer.cpp b/Source/core/rendering/RenderLayer.cpp
index 2e5e260ea0e15f0a2537a147ad40e33b2640eb5e..0c2966febc71ff1b226fe4c518dbd917faa96b8c 100644
--- a/Source/core/rendering/RenderLayer.cpp
+++ b/Source/core/rendering/RenderLayer.cpp
@@ -3331,6 +3331,7 @@ void RenderLayer::paintLayerContents(GraphicsContext* context, const LayerPainti
     bool shouldPaintNormalFlowAndPosZOrderLists = isPaintingCompositedForeground;
     bool shouldPaintOverlayScrollbars = isPaintingOverlayScrollbars;
     bool shouldPaintMask = (paintFlags & PaintLayerPaintingCompositingMaskPhase) && shouldPaintContent && renderer()->hasMask() && !selectionOnly;
+    bool shouldPaintClippingMask = (paintFlags & PaintLayerPaintingChildClippingMaskPhase) && renderer()->style()->hasBorderRadius() && shouldPaintContent && !selectionOnly;
 
     PaintBehavior paintBehavior = PaintBehaviorNormal;
     if (paintFlags & PaintLayerPaintingSkipRootBackground)
@@ -3386,6 +3387,11 @@ void RenderLayer::paintLayerContents(GraphicsContext* context, const LayerPainti
     if (shouldPaintMask)
         paintMaskForFragments(layerFragments, context, localPaintingInfo, paintingRootForRenderer);
 
+    if (shouldPaintClippingMask) {
+        // Paint the border radius mask for the fragments.
+        paintChildClippingMaskForFragments(layerFragments, context, localPaintingInfo, paintingRootForRenderer);
+    }
+
     // End our transparency layer
     if (haveTransparency && m_usedTransparency && !m_paintingInsideReflection) {
         context->endLayer();
@@ -3688,6 +3694,26 @@ void RenderLayer::paintMaskForFragments(const LayerFragments& layerFragments, Gr
     }
 }
 
+void RenderLayer::paintChildClippingMaskForFragments(const LayerFragments& layerFragments, GraphicsContext* context, const LayerPaintingInfo& localPaintingInfo,
+    RenderObject* paintingRootForRenderer)
+{
+    for (size_t i = 0; i < layerFragments.size(); ++i) {
+        const LayerFragment& fragment = layerFragments.at(i);
+        if (!fragment.shouldPaintContent)
+            continue;
+
+        if (localPaintingInfo.clipToDirtyRect)
+            clipToRect(localPaintingInfo.rootLayer, context, localPaintingInfo.paintDirtyRect, fragment.foregroundRect, IncludeSelfForBorderRadius); // Child clipping mask painting will handle clipping to self.
+
+        // Paint the the clipped mask.
+        PaintInfo paintInfo(context, pixelSnappedIntRect(fragment.backgroundRect.rect()), PaintPhaseClippingMask, PaintBehaviorNormal, paintingRootForRenderer, localPaintingInfo.region, 0, 0, localPaintingInfo.rootLayer->renderer());
+        renderer()->paint(paintInfo, toPoint(fragment.layerBounds.location() - renderBoxLocation() + localPaintingInfo.subPixelAccumulation));
+
+        if (localPaintingInfo.clipToDirtyRect)
+            restoreClip(context, localPaintingInfo.paintDirtyRect, fragment.foregroundRect);
+    }
+}
+
 void RenderLayer::paintOverflowControlsForFragments(const LayerFragments& layerFragments, GraphicsContext* context, const LayerPaintingInfo& localPaintingInfo)
 {
     for (size_t i = 0; i < layerFragments.size(); ++i) {
@@ -5007,6 +5033,11 @@ bool RenderLayer::hasCompositedMask() const
     return m_backing && m_backing->hasMaskLayer();
 }
 
+bool RenderLayer::hasCompositedClippingMask() const
+{
+    return m_backing && m_backing->hasChildClippingMaskLayer();
+}
+
 GraphicsLayer* RenderLayer::layerForScrolling() const
 {
     return m_backing ? m_backing->scrollingContentsLayer() : 0;