Call Element::rebuildLayoutTree from Document::updateStyle directly

third_party/WebKit/Source/core/dom/Element.cpp

Index: third_party/WebKit/Source/core/dom/Element.cpp
diff --git a/third_party/WebKit/Source/core/dom/Element.cpp b/third_party/WebKit/Source/core/dom/Element.cpp
index fd79b779eabf4799b7ba977e3148225b61db4544..5d45afb6bb9798e2f65262e2827a7b477448bb8f 100644
--- a/third_party/WebKit/Source/core/dom/Element.cpp
+++ b/third_party/WebKit/Source/core/dom/Element.cpp
@@ -183,7 +183,6 @@ Element::Element(const QualifiedName& tagName,
     : ContainerNode(document, type), m_tagName(tagName) {}
 
 Element::~Element() {
-  DCHECK(needsAttach());

[nainar, 2016/11/29 06:13:39]

See comment in ContainerNode destructor. 

 }
 
 inline ElementRareData* Element::elementRareData() const {
@@ -1662,7 +1661,7 @@ void Element::attachLayoutTree(const AttachContext& context) {
 
   // We've already been through detach when doing an attach, but we might
   // need to clear any state that's been added since then.
-  if (hasRareData() && getStyleChangeType() == NeedsReattachStyleChange) {

[nainar, 2016/11/29 06:13:39]

We are setting the corresponging NeedsReattachLayoutTree - check that here
instead. 

+  if (hasRareData() && needsReattachLayoutTree()) {
     ElementRareData* data = elementRareData();
     data->clearComputedStyle();
   }
@@ -1750,7 +1749,7 @@ void Element::detachLayoutTree(const AttachContext& context) {
 
   setNeedsResizeObserverUpdate();
 
-  DCHECK(needsAttach());
+  DCHECK(needsReattachLayoutTree());
 }
 
 bool Element::pseudoStyleCacheIsInvalid(const ComputedStyle* currentStyle,
@@ -1856,7 +1855,6 @@ void Element::recalcStyle(StyleRecalcChange change, Text* nextTextSibling) {
     if (parentComputedStyle())
       change = recalcOwnStyle(change, nextTextSibling);
     clearNeedsStyleRecalc();
-    clearNeedsReattachLayoutTree();
   }
 
   // If we reattached we don't need to recalc the style of our descendants
@@ -1886,9 +1884,6 @@ void Element::recalcStyle(StyleRecalcChange change, Text* nextTextSibling) {
     // non-floating we have to take it into account for the first letter.
     updatePseudoElement(PseudoIdFirstLetter,
                         childNeedsStyleRecalc() ? Force : change);
-
-    clearChildNeedsStyleRecalc();
-    clearChildNeedsReattachLayoutTree();
   }
 
   if (hasCustomStyleCallbacks())
@@ -1948,7 +1943,7 @@ StyleRecalcChange Element::recalcOwnStyle(StyleRecalcChange change,
     styleReattachData.nextTextSibling = nextTextSibling;
     document().addStyleReattachData(*this, styleReattachData);
     setNeedsReattachLayoutTree();
-    return rebuildLayoutTree();
+    return Reattach;
   }
 
   DCHECK(oldStyle);
@@ -1989,23 +1984,31 @@ StyleRecalcChange Element::recalcOwnStyle(StyleRecalcChange change,
   return localChange;
 }
 
-StyleRecalcChange Element::rebuildLayoutTree() {
+void Element::rebuildLayoutTree() {
   DCHECK(inActiveDocument());
+  DCHECK(!needsStyleRecalc());
+  DCHECK(!childNeedsStyleRecalc());
+  DCHECK(parentNode());
+  DCHECK(parentNode()->childNeedsReattachLayoutTree());
+
   StyleReattachData styleReattachData = document().getStyleReattachData(*this);
   AttachContext reattachContext;
   reattachContext.resolvedStyle = styleReattachData.computedStyle.get();
-  bool layoutObjectWillChange = needsAttach() || layoutObject();
+  bool layoutObjectWillChange = needsReattachLayoutTree() || layoutObject();
 
-  // We are calling Element::rebuildLayoutTree() from inside
-  // Element::recalcOwnStyle where we set the NeedsReattachLayoutTree
-  // flag - so needsReattachLayoutTree() should always be true.
-  DCHECK(parentNode());
-  DCHECK(parentNode()->childNeedsReattachLayoutTree());
-  DCHECK(needsReattachLayoutTree());
-  reattachLayoutTree(reattachContext);
-  // Since needsReattachLayoutTree() is always true we go into
-  // reattachLayoutTree() which reattaches all the descendant
-  // sub-trees. At this point no child should need reattaching.
+  if (needsReattachLayoutTree()) {
+    reattachLayoutTree(reattachContext);
+  } else if (childNeedsReattachLayoutTree()) {
+    SelectorFilterParentScope filterScope(*this);
+    StyleSharingDepthScope sharingScope(*this);
+    reattachPseudoElementLayoutTree(PseudoIdBefore);
+    rebuildShadowRootLayoutTree();
+    rebuildDescendantLayoutTree();
+    reattachPseudoElementLayoutTree(PseudoIdAfter);
+    reattachPseudoElementLayoutTree(PseudoIdBackdrop);
+    reattachPseudoElementLayoutTree(PseudoIdFirstLetter);
+  }
+  DCHECK(!needsReattachLayoutTree());
   DCHECK(!childNeedsReattachLayoutTree());
 
   if (layoutObjectWillChange || layoutObject()) {
@@ -2014,9 +2017,29 @@ StyleRecalcChange Element::rebuildLayoutTree() {
     // or store it.
     // The choice is between increased time and increased memory complexity.
     reattachWhitespaceSiblingsIfNeeded(styleReattachData.nextTextSibling);
-    return Reattach;
   }
-  return ReattachNoLayoutObject;
+}
+
+void Element::rebuildShadowRootLayoutTree() {
+  DCHECK(!needsStyleRecalc());
+  DCHECK(!childNeedsStyleRecalc());
+  DCHECK(!needsReattachLayoutTree());
+  for (ShadowRoot* root = youngestShadowRoot(); root;
+       root = root->olderShadowRoot()) {
+    if (root->needsReattachLayoutTree() || root->childNeedsReattachLayoutTree())
+      root->rebuildLayoutTree();
+  }
+}
+
+void Element::reattachPseudoElementLayoutTree(PseudoId pseudoId) {
+  DCHECK(!needsStyleRecalc());
+  DCHECK(!childNeedsStyleRecalc());
+  DCHECK(!needsReattachLayoutTree());
+  if (PseudoElement* element = pseudoElement(pseudoId)) {
+    if (element->needsReattachLayoutTree() ||
+        element->childNeedsReattachLayoutTree())
+      element->rebuildLayoutTree();
+  }
 }
 
 void Element::updateCallbackSelectors(const ComputedStyle* oldStyle,
@@ -3243,8 +3266,9 @@ void Element::createPseudoElementIfNeeded(PseudoId pseudoId) {
   if (pseudoId == PseudoIdBackdrop)
     document().addToTopLayer(element, this);
   element->insertedInto(this);
+  element->setLocalNeedsReattachLayoutTree();

[nainar, 2016/11/29 06:13:39]

Only the Pseudo Element needs to be reattached. 

   element->attachLayoutTree();
-
+  DCHECK(!element->needsReattachLayoutTree());
   InspectorInstrumentation::pseudoElementCreated(element);
 
   ensureElementRareData().setPseudoElement(pseudoId, element);