Remove invalidation code when creating new PaintLayers.

This code was originally added in [1]. The web_test added in that
CL still passes, as does a subsequent related unittest added in another
CL (PaintLayerPainterTest, PaintPhasesUpdateOnLayerAddition).

I'm not sure what caused these to keep passing with the code removed -
there is a reference in [1] to re-use of DisplayItemClient pointers,
perhaps that was improved since then?

[1] https://codereview.chromium.org/1403963002

The bug reported in issue 541544 also does not reproduce with this CL
applied.

Bug: 1104794

Change-Id: I91addcea57c217dd1f971fcc4dbae0cd518c7011
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2307610
Commit-Queue: Chris Harrelson <chrishtr@chromium.org>
Reviewed-by: Xianzhu Wang <wangxianzhu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#790106}

third_party/blink/renderer/core/paint/object_paint_invalidator.cc

@@ -148,26 +148,6 @@ void ObjectPaintInvalidator::
       });
 }
 
-void ObjectPaintInvalidator::
-    InvalidatePaintIncludingNonSelfPaintingLayerDescendants() {
-  SlowSetPaintingLayerNeedsRepaint();
-  // This method may be used to invalidate paint of objects changing paint
-  // invalidation container.
-  struct Helper {
-    static void Traverse(const LayoutObject& object) {
-      object.GetMutableForPainting().SetShouldDoFullPaintInvalidation(
-          PaintInvalidationReason::kCompositing);
-      for (LayoutObject* child = object.SlowFirstChild(); child;
-           child = child->NextSibling()) {
-        if (!child->HasLayer() ||
-            !ToLayoutBoxModelObject(child)->Layer()->IsSelfPaintingLayer())
-          Traverse(*child);
-      }
-    }
-  };
-  Helper::Traverse(object_);
-}
-
 #if DCHECK_IS_ON()
 void ObjectPaintInvalidator::CheckPaintLayerNeedsRepaint() {
   DCHECK(!object_.PaintingLayer() ||

third_party/blink/renderer/core/paint/object_paint_invalidator.h

@@ -56,7 +56,6 @@ class CORE_EXPORT ObjectPaintInvalidator {
   }
 
   void InvalidatePaintIncludingNonCompositingDescendants();
-  void InvalidatePaintIncludingNonSelfPaintingLayerDescendants();
 
  protected:
 #if DCHECK_IS_ON()

third_party/blink/renderer/core/paint/paint_layer.cc

@@ -1392,25 +1392,7 @@ void PaintLayer::InsertOnlyThisLayerAfterStyleChange() {
        curr = curr->NextSibling())
     curr->MoveLayers(parent_, this);
 
-  // If the previous directly composited container is not a stacking context and
-  // this object is stacked content, creating this layer may cause this object
-  // and its descendants to change paint invalidation container.
-  bool did_set_paint_invalidation = false;
-  if (!RuntimeEnabledFeatures::CompositeAfterPaintEnabled() &&
-      !IsA<LayoutView>(GetLayoutObject()) && GetLayoutObject().IsRooted() &&
-      GetLayoutObject().IsStacked()) {
-    const LayoutBoxModelObject& previous_directly_compositable_container =
-        GetLayoutObject().Parent()->DirectlyCompositableContainer();
-    if (!previous_directly_compositable_container.IsStackingContext()) {
-      ObjectPaintInvalidator(GetLayoutObject())
-          .InvalidatePaintIncludingNonSelfPaintingLayerDescendants();
-      // Set needsRepaint along the original compositingContainer chain.
-      GetLayoutObject().Parent()->EnclosingLayer()->SetNeedsRepaint();
-      did_set_paint_invalidation = true;
-    }
-  }
-
-  if (!did_set_paint_invalidation && IsSelfPaintingLayer() && parent_) {
+  if (IsSelfPaintingLayer() && parent_) {
     if (PaintLayer* enclosing_self_painting_layer =
             parent_->EnclosingSelfPaintingLayer())
       MergeNeedsPaintPhaseFlagsFrom(*enclosing_self_painting_layer);