[SPv2] Add CSS mask support

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

Index: third_party/WebKit/Source/core/paint/PaintLayer.cpp
diff --git a/third_party/WebKit/Source/core/paint/PaintLayer.cpp b/third_party/WebKit/Source/core/paint/PaintLayer.cpp
index c86eecd23bcb11405ff93ff668cc7856c6edd9dd..aa36e2a73c8e65bf52ec7bad249a1ac2a4d64c5d 100644
--- a/third_party/WebKit/Source/core/paint/PaintLayer.cpp
+++ b/third_party/WebKit/Source/core/paint/PaintLayer.cpp
@@ -2651,7 +2651,10 @@ void PaintLayer::setGroupedMapping(CompositedLayerMapping* groupedMapping,
     groupedMapping->setNeedsGraphicsLayerUpdate(GraphicsLayerUpdateSubtree);
 }
 
-bool PaintLayer::hasCompositedMask() const {
+bool PaintLayer::maskBlendingAppliedByCompositor() const {

[chrishtr, 2017/02/11 23:55:11]

In SPv2 mode, it's not really "applied by compositor", but
insted applied by the property node, which may or may not
end up surviving squashing in PaintArtifactCompositor.
Maybe just add a TODO to rename this after launching?

[trchen, 2017/02/13 21:12:02]

The property tree is the representation of the effect and will be ultimately
applied by PaintArtifactCompositor/cc. IMO it isn't confusing if we consider PAC
a part of the compositor?

Anyway, I don't even think this should be a PaintLayer method. This information
really belongs to paintInfo.flags. We shouldn't lose sleep over its naming. :D

[chrishtr, 2017/02/13 23:23:49]

ok

+  DCHECK(m_layoutObject->hasMask());
+  if (RuntimeEnabledFeatures::slimmingPaintV2Enabled())
+    return true;
   return m_rareData && m_rareData->compositedLayerMapping &&
          m_rareData->compositedLayerMapping->hasMaskLayer();
 }