Fix paint property under-invalidation checking about reference filters

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 a0a17d3962ef13e7d138575fc7b25be600a0f5ca..582ab106323fd7b67af9a1a8c668fff80b82f8a6 100644
--- a/third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp
+++ b/third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp
@@ -382,11 +382,19 @@ void PaintPropertyTreeBuilder::updateEffect(
       effectNodeNeeded = true;
 
     CompositorFilterOperations filter;
+#if DCHECK_IS_ON()
+    FilterOperations styleFilterOperations;
+#endif
     if (object.isSVG() && !object.isSVGRoot()) {
       // TODO(trchen): SVG caches filters in SVGResources. Implement it.
     } else if (PaintLayer* layer = toLayoutBoxModelObject(object).layer()) {
       // TODO(trchen): Eliminate PaintLayer dependency.
+#if DCHECK_IS_ON()
+      filter = layer->createCompositorFilterOperationsForFilter(
+          style, &styleFilterOperations);
+#else
       filter = layer->createCompositorFilterOperationsForFilter(style);
+#endif
     }
 
     const ClipPaintPropertyNode* outputClip = context.inputClipOfCurrentEffect;
@@ -422,6 +430,9 @@ void PaintPropertyTreeBuilder::updateEffect(
       context.forceSubtreeUpdate |= properties.updateEffect(
           context.currentEffect, context.current.transform, outputClip,
           std::move(filter), opacity);
+#if DCHECK_IS_ON()
+      properties.setStyleFilterOperations(styleFilterOperations);

[pdr., 2016/12/08 02:00:41]

How much additional value will these checks give us? Looking at
ReferenceFilterOperation::operator==, I think we just check the style
(style="filter: url(#cat)" != style="filter: url('#dog')") but not the actual
value, such as if the #dog element's children change.

equalsIgnoringReferenceFilters already catches many cases such as when the total
number of operations change. WDYT of just relying on
equalsIgnoringReferenceFilters and not doing the extra checks of
styleFilterOperations? This will mean we fail to catch some cases, but it lets
us avoid adding a new pattern to FindObjectPropertiesNeedingUpdateScope and new
members to ObjectPaintProperties.

[Xianzhu, 2016/12/08 17:34:35]

You are right. The little additional value is not worth the complexity.
Done.

+#endif
     } else {
       if (auto* properties = object.getMutableForPainting().paintProperties())
         context.forceSubtreeUpdate |= properties->clearEffect();