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 7c286936357b055b17ba342c2581c8daf2be69cc..c09f3f45f0f1165eaa056cd560d4cff48d7d99a7 100644
--- a/third_party/WebKit/Source/core/dom/Element.cpp
+++ b/third_party/WebKit/Source/core/dom/Element.cpp
@@ -1855,10 +1855,12 @@ void Element::recalcStyle(StyleRecalcChange change, Text* nextTextSibling) {
           elementAnimations->setAnimationStyleChange(false);
       }
     }
-    if (parentComputedStyle())
+    if (parentComputedStyle()) {
       change = recalcOwnStyle(change, nextTextSibling);
+    } else {
+      clearNeedsReattachLayoutTree();

[nainar, 2016/12/07 14:48:21]

In case we don't perform recalcOwnStyle we will never clear the
NeedsReattachLayoutTree flag which is set on the creation of each Node. Clear
that here. 

[Bugs Nash, 2016/12/07 23:21:44]

good explanation, would be useful in a code comment

[nainar, 2016/12/07 23:49:10]

Done locally.

+    }
     clearNeedsStyleRecalc();
-    clearNeedsReattachLayoutTree();
   }
 
   // If we reattached we don't need to recalc the style of our descendants
@@ -1890,7 +1892,6 @@ void Element::recalcStyle(StyleRecalcChange change, Text* nextTextSibling) {
                         childNeedsStyleRecalc() ? Force : change);
 
     clearChildNeedsStyleRecalc();
-    clearChildNeedsReattachLayoutTree();
   }
 
   if (hasCustomStyleCallbacks())
@@ -1950,7 +1951,7 @@ StyleRecalcChange Element::recalcOwnStyle(StyleRecalcChange change,
     styleReattachData.nextTextSibling = nextTextSibling;
     document().addStyleReattachData(*this, styleReattachData);
     setNeedsReattachLayoutTree();
-    return rebuildLayoutTree();
+    return Reattach;
   }
 
   DCHECK(oldStyle);
@@ -1991,23 +1992,30 @@ StyleRecalcChange Element::recalcOwnStyle(StyleRecalcChange change,
   return localChange;
 }
 
-StyleRecalcChange Element::rebuildLayoutTree() {
+void Element::rebuildLayoutTree() {
   DCHECK(inActiveDocument());
+  DCHECK(!needsStyleRecalc());
+  DCHECK(!childNeedsStyleRecalc());
+  DCHECK(parentNode());
+
   StyleReattachData styleReattachData = document().getStyleReattachData(*this);
   AttachContext reattachContext;
   reattachContext.resolvedStyle = styleReattachData.computedStyle.get();
   bool layoutObjectWillChange = needsAttach() || 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();
+    rebuildDescendantLayoutTrees();
+    reattachPseudoElementLayoutTree(PseudoIdAfter);
+    reattachPseudoElementLayoutTree(PseudoIdBackdrop);
+    reattachPseudoElementLayoutTree(PseudoIdFirstLetter);
+  }
+  DCHECK(!needsReattachLayoutTree());
   DCHECK(!childNeedsReattachLayoutTree());
 
   if (layoutObjectWillChange || layoutObject()) {
@@ -2016,9 +2024,29 @@ 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,
@@ -3246,7 +3274,6 @@ void Element::createPseudoElementIfNeeded(PseudoId pseudoId) {
     document().addToTopLayer(element, this);
   element->insertedInto(this);
   element->attachLayoutTree();
-

[Bugs Nash, 2016/12/07 23:21:44]

was this intentional?

[nainar, 2016/12/07 23:49:10]

Nope - haven't sanitized the code for erroneous formating issues. Fixed this
issue locally. 

   InspectorInstrumentation::pseudoElementCreated(element);
 
   ensureElementRareData().setPseudoElement(pseudoId, element);