[SPInvalidation] Update paint properties when layer or paintsWithTransform status change

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

Index: third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp
diff --git a/third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp b/third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp
index e388aaff88dbc94db86bc74a32d1a0c531bf55e1..61fc5abb3983766c251e52fe39ed7285f05e80cd 100644
--- a/third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp
+++ b/third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp
@@ -219,7 +219,8 @@ void PaintPropertyTreeBuilder::updatePaintOffsetTranslation(
              context.current.paintOffset != LayoutPoint()) {
     // TODO(trchen): Eliminate PaintLayer dependency.
     PaintLayer* layer = toLayoutBoxModelObject(object).layer();
-    if (layer && layer->paintsWithTransform(GlobalPaintNormalPhase))
+    if (layer &&
+        layer->paintsWithTransform(GlobalPaintFlattenCompositingLayers))

[Xianzhu, 2016/12/14 18:41:00]

This avoids paintsWithTransform from depending on compositing state, making it
possible to use the same condition in LayoutBoxModelObject::styleDidChange() for
setting needsPaintPropertyUpdate.

[pdr., 2016/12/14 21:52:53]

"compositingState() != PaintsIntoOwnBacking" should always be false in spv2, so
I think we should track this differently. It feels like a layering violation to
use values on the paint property tree for detecting changes. I think we should
be able to catch these changes just based on style. Would it be sufficient to
check for cases where a transform style or fixed style is added or removed?

[Xianzhu, 2016/12/14 22:02:31]

When you posted this comment, I just uploaded a patch-set adding TODO(chrishtr)
here and in LayoutBoxModelObject::styleDidChange() because Chris seems about to
make further change about this (https://codereview.chromium.org/2570423003), and
I'd like to leave the follow-up of the above code to Chris.

I changed the parameter of paintsWithTransform in this CL to ensure correctness
for SlimmingPaintInvalidation.

       usesPaintOffsetTranslation = true;
   }