[SPv2] Adds pre-computed paint property context to PaintLayer.

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 f48b8772ce4a0e0500b69506c1569b7940b483ce..bced6e62f5cecec988c3ccd8623b6c01a5e8d09f 100644
--- a/third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp
+++ b/third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp
@@ -310,6 +310,20 @@ static void updateOutOfFlowContext(const LayoutObject& object, bool createdNewTr
     }
 }
 
+PassOwnPtr<ObjectPaintProperties::PropertyTreeContext> recordTreeContextIfNeeded(LayoutObject& object, const PaintPropertyTreeBuilderContext& context)
+{
+    // Note: Currently only layer painter makes use of the pre-computed context. This condition can be changed.

[pdr., 2016/02/04 04:54:01]

I tried to think of a case where this would be used for non-PaintLayers (e.g.,
svg, etc) but couldn't think of one. Can you think of a future case where we
would need to use the local context other than layers? I see the local context
as mainly working around the not-very-sane rules of overflow clipping but I
don't think we will be adding more of those cases.

[trchen, 2016/02/04 23:08:40]

I don't know. It may be used by the merge algorithm for updating property nodes
for cached display items? Anyway the comments just want to say there will be no
adverse effect to loosen the condition.

+    if (!object.hasLayer())
+        return nullptr;
+
+    OwnPtr<ObjectPaintProperties::PropertyTreeContext> recordedContext = adoptPtr(new ObjectPaintProperties::PropertyTreeContext);
+    recordedContext->paintOffset = context.paintOffset;
+    recordedContext->properties.transform = context.currentTransform;
+    recordedContext->properties.clip = context.currentClip;
+    recordedContext->properties.effect = context.currentEffect;
+    return recordedContext.release();
+}
+
 void PaintPropertyTreeBuilder::walk(LayoutObject& object, const PaintPropertyTreeBuilderContext& context)
 {
     PaintPropertyTreeBuilderContext localContext(context);
@@ -318,6 +332,7 @@ void PaintPropertyTreeBuilder::walk(LayoutObject& object, const PaintPropertyTre
     RefPtr<TransformPaintPropertyNode> newTransformNodeForPaintOffsetTranslation = createPaintOffsetTranslationIfNeeded(object, localContext);
     RefPtr<TransformPaintPropertyNode> newTransformNodeForTransform = createTransformIfNeeded(object, localContext);
     RefPtr<EffectPaintPropertyNode> newEffectNode = createEffectIfNeeded(object, localContext);
+    OwnPtr<ObjectPaintProperties::PropertyTreeContext> newRecordedContext = recordTreeContextIfNeeded(object, localContext);
     RefPtr<ClipPaintPropertyNode> newClipNodeForOverflowClip = createOverflowClipIfNeeded(object, localContext);
     // TODO(trchen): Insert flattening transform here, as specified by
     // http://www.w3.org/TR/css3-transforms/#transform-style-property
@@ -325,14 +340,15 @@ void PaintPropertyTreeBuilder::walk(LayoutObject& object, const PaintPropertyTre
     RefPtr<TransformPaintPropertyNode> newTransformNodeForScrollTranslation = createScrollTranslationIfNeeded(object, localContext);
     updateOutOfFlowContext(object, newTransformNodeForTransform, localContext);
 
-    if (newTransformNodeForPaintOffsetTranslation || newTransformNodeForTransform || newEffectNode || newClipNodeForOverflowClip || newTransformNodeForPerspective || newTransformNodeForScrollTranslation) {
+    if (newTransformNodeForPaintOffsetTranslation || newTransformNodeForTransform || newEffectNode || newClipNodeForOverflowClip || newTransformNodeForPerspective || newTransformNodeForScrollTranslation || newRecordedContext) {
         OwnPtr<ObjectPaintProperties> updatedPaintProperties = ObjectPaintProperties::create(
             newTransformNodeForPaintOffsetTranslation.release(),
             newTransformNodeForTransform.release(),
             newEffectNode.release(),
             newClipNodeForOverflowClip.release(),
             newTransformNodeForPerspective.release(),
-            newTransformNodeForScrollTranslation.release());
+            newTransformNodeForScrollTranslation.release(),
+            newRecordedContext.release());
         object.setObjectPaintProperties(updatedPaintProperties.release());
     } else {
         object.clearObjectPaintProperties();