Fix border radius on composited children.

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

Index: third_party/WebKit/Source/core/paint/PaintLayerPainter.cpp
diff --git a/third_party/WebKit/Source/core/paint/PaintLayerPainter.cpp b/third_party/WebKit/Source/core/paint/PaintLayerPainter.cpp
index eea4ca3e7b43624d3f5d5a8380a852969219642a..aa6677513f8ea6b4701680449d1c69b363082369 100644
--- a/third_party/WebKit/Source/core/paint/PaintLayerPainter.cpp
+++ b/third_party/WebKit/Source/core/paint/PaintLayerPainter.cpp
@@ -327,7 +327,8 @@ PaintLayerPainter::PaintResult PaintLayerPainter::paintLayerContents(
   // scrolling contents and scrollbars.
   if (m_paintLayer.layoutObject()->hasClipPath() &&
       (!m_paintLayer.needsCompositedScrolling() ||
-       (paintFlags & PaintLayerPaintingChildClippingMaskPhase))) {
+       (paintFlags & (PaintLayerPaintingChildClippingMaskPhase |
+                      PaintLayerPaintingAncestorClippingMaskPhase)))) {
     paintingInfo.ancestorHasClipPathClipping = true;
 
     LayoutRect referenceBox(m_paintLayer.boxForClipPath());
@@ -384,18 +385,21 @@ PaintLayerPainter::PaintResult PaintLayerPainter::paintLayerContents(
     // SPv2.  Related thread
     // https://groups.google.com/a/chromium.org/forum/#!topic/graphics-dev/81XuWFf-mxM
     if (fragmentPolicy == ForceSingleFragment ||
-        RuntimeEnabledFeatures::slimmingPaintV2Enabled())
+        RuntimeEnabledFeatures::slimmingPaintV2Enabled()) {
       m_paintLayer.appendSingleFragmentIgnoringPagination(
           layerFragments, localPaintingInfo.rootLayer,
           localPaintingInfo.paintDirtyRect, cacheSlot,
-          IgnoreOverlayScrollbarSize, respectOverflowClip, &offsetFromRoot,
-          localPaintingInfo.subPixelAccumulation);
-    else
-      m_paintLayer.collectFragments(layerFragments, localPaintingInfo.rootLayer,
-                                    localPaintingInfo.paintDirtyRect, cacheSlot,
-                                    IgnoreOverlayScrollbarSize,
-                                    respectOverflowClip, &offsetFromRoot,
-                                    localPaintingInfo.subPixelAccumulation);
+          IgnoreOverlayScrollbarSize, respectOverflowClip,
+          paintFlags & PaintLayerPaintingAncestorClippingMaskPhase,
+          &offsetFromRoot, localPaintingInfo.subPixelAccumulation);
+    } else {
+      m_paintLayer.collectFragments(
+          layerFragments, localPaintingInfo.rootLayer,
+          localPaintingInfo.paintDirtyRect, cacheSlot,
+          IgnoreOverlayScrollbarSize, respectOverflowClip,
+          paintFlags & PaintLayerPaintingAncestorClippingMaskPhase,
+          &offsetFromRoot, localPaintingInfo.subPixelAccumulation);
+    }
 
     if (shouldPaintContent) {
       // TODO(wangxianzhu): This is for old slow scrolling. Implement similar
@@ -492,7 +496,8 @@ PaintLayerPainter::PaintResult PaintLayerPainter::paintLayerContents(
       shouldPaintContent && m_paintLayer.layoutObject()->hasMask() &&
       !selectionOnly;
   bool shouldPaintClippingMask =
-      (paintFlags & PaintLayerPaintingChildClippingMaskPhase) &&
+      (paintFlags & (PaintLayerPaintingChildClippingMaskPhase |
+                     PaintLayerPaintingAncestorClippingMaskPhase)) &&
       shouldPaintContent && !selectionOnly;
 
   if (shouldPaintMask)
@@ -571,6 +576,7 @@ PaintLayerPainter::PaintResult PaintLayerPainter::paintLayerWithTransform(
       object->container() == view && view->pageLogicalHeight();
   PaintLayer* paginationLayer = m_paintLayer.enclosingPaginationLayer();
   PaintLayerFragments fragments;
+
   // TODO(crbug.com/619094): Figure out the correct behaviour for fixed position
   // objects in paged media with vertical writing modes.
   if (isFixedPosObjectInPagedMedia && view->isHorizontalWritingMode()) {
@@ -612,7 +618,7 @@ PaintLayerPainter::PaintResult PaintLayerPainter::paintLayerWithTransform(
     // here.
     paginationLayer->collectFragments(
         fragments, paintingInfo.rootLayer, paintingInfo.paintDirtyRect,
-        cacheSlot, IgnoreOverlayScrollbarSize, respectOverflowClip, 0,
+        cacheSlot, IgnoreOverlayScrollbarSize, respectOverflowClip, false, 0,
         paintingInfo.subPixelAccumulation, &transformedExtent);
   } else {
     // We don't need to collect any fragments in the regular way here. We have
@@ -828,6 +834,27 @@ void PaintLayerPainter::paintOverflowControlsForFragments(
   }
 }
 
+LayoutPoint PaintLayerPainter::fragmentOffsetForAncestorClipMask(
+    const LayoutPoint& originalFragmentOffset) {
+  // The clipping container that will be used to define the clip and the
+  // child layer with respect to which the fragment offset is defined share
+  // a layer root. When the clip is recorded we will be using the clipping
+  // container's layer's offset to the root to position the clip. Hence we
+  // must convert the fragment offset into a corresponding offset in the
+  // clipping container's layer coordinates. To do that, we find the
+  // originalFragmentOffset's coordinate in the root layer, fragmentDelta.
+  // We also find the offset of the clipping container's origin in the root
+  // layer's coordinates, clippingDelta. clippingDelta - fragmentDelta gives
+  // the fragment's position in the root layer. But we need the position in
+  // the clipping layer coords, and we subtract clippingDelta to get that. The
+  // resulting offset is -fragmentDelta.
+  DCHECK_EQ(m_paintLayer.root(),
+            m_paintLayer.clippingContainer()->enclosingLayer()->root());
+  LayoutPoint fragmentDelta(originalFragmentOffset);
+  m_paintLayer.convertToLayerCoords(m_paintLayer.root(), fragmentDelta);
+  return LayoutPoint(-fragmentDelta.x(), -fragmentDelta.y());
+}
+
 void PaintLayerPainter::paintFragmentWithPhase(
     PaintPhase phase,
     const PaintLayerFragment& fragment,
@@ -856,9 +883,21 @@ void PaintLayerPainter::paintFragmentWithPhase(
         break;
     }
 
-    clipRecorder.emplace(context, *m_paintLayer.layoutObject(), clipType,
-                         clipRect, &paintingInfo, fragment.paginationOffset,
-                         paintFlags, clippingRule);
+    // When painting the clipping mask for a composited child, we pass
+    // the clipping container object as the layoutObject to provide the clip.
+    // The recorder assumes the fragment is positioned in that objects's
+    // layer coordinates, so we also convert that.
+    if (paintFlags & PaintLayerPaintingAncestorClippingMaskPhase) {
+      clipRecorder.emplace(
+          context, *(toLayoutBoxModelObject(m_paintLayer.clippingContainer())),
+          clipType, clipRect, &paintingInfo,
+          fragmentOffsetForAncestorClipMask(fragment.paginationOffset),
+          paintFlags, clippingRule);
+    } else {
+      clipRecorder.emplace(context, *m_paintLayer.layoutObject(), clipType,
+                           clipRect, &paintingInfo, fragment.paginationOffset,
+                           paintFlags, clippingRule);
+    }
   }
 
   LayoutRect newCullRect(clipRect.rect());
@@ -892,6 +931,7 @@ void PaintLayerPainter::paintFragmentWithPhase(
                       paintingInfo.getGlobalPaintFlags(), paintFlags,
                       paintingInfo.rootLayer->layoutObject());
 
+  // TODO(schenney): This is the wrong object for painting AncestorClippingMask.

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

No it's not. It's the wrong object for all the clipping code, not the painting
code. Remove this comment.

   m_paintLayer.layoutObject()->paint(paintInfo, paintOffset);
 }