Check whether a text node may be about to be redistributed in ShouldUpdateLayoutByReattaching()

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

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights
  * reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 13 matching lines @@
 
 #include "bindings/core/v8/ExceptionState.h"
 #include "core/SVGNames.h"
 #include "core/css/resolver/StyleResolver.h"
 #include "core/dom/ExceptionCode.h"
 #include "core/dom/FirstLetterPseudoElement.h"
 #include "core/dom/LayoutTreeBuilder.h"
 #include "core/dom/LayoutTreeBuilderTraversal.h"
 #include "core/dom/NodeComputedStyle.h"
 #include "core/dom/NodeTraversal.h"
+#include "core/dom/shadow/ElementShadow.h"
 #include "core/dom/shadow/ShadowRoot.h"
 #include "core/events/ScopedEventQueue.h"
 #include "core/layout/LayoutText.h"
 #include "core/layout/LayoutTextCombine.h"
 #include "core/layout/LayoutTextFragment.h"
 #include "core/layout/api/LayoutTextItem.h"
 #include "core/layout/svg/LayoutSVGInlineText.h"
 #include "core/svg/SVGForeignObjectElement.h"
 #include "platform/bindings/DOMDataStore.h"
 #include "platform/wtf/text/CString.h"
@@ skipping 395 matching lines @@
   if (!text_layout_object)
     return true;
   // In general we do not want to branch on lifecycle states such as
   // |childNeedsDistributionRecalc|, but this code tries to figure out if we can
   // use an optimized code path that avoids reattach.
   if (!text_node.GetDocument().ChildNeedsDistributionRecalc() &&
       !text_node.TextLayoutObjectIsNeeded(*text_layout_object->Style(),
                                           *text_layout_object->Parent())) {
     return true;
   }
+  // Check whether this node may be about to be redistributed.
+  if (text_node.ParentElementShadow() &&

[yosin_UTC9, 2017/06/02 07:47:43]

What is happend when Text is descendant of shadow host? 

e.g.
<div id="shadowHost"><span>My parent is not shadow host</span></div>

+      text_node.ParentElementShadow()->NeedsDistributionRecalc()) {
+    return true;
+  }
   if (text_layout_object->IsTextFragment()) {
     // Changes of |textNode| may change first letter part, so we should
     // reattach.
     return ToLayoutTextFragment(text_layout_object)
         ->GetFirstLetterPseudoElement();
   }
   return false;
 }
 
 void Text::UpdateTextLayoutObject(unsigned offset_of_replaced_data,
@@ skipping 12 matching lines @@
 
 Text* Text::CloneWithData(const String& data) {
   return Create(GetDocument(), data);
 }
 
 DEFINE_TRACE(Text) {
   CharacterData::Trace(visitor);
 }
 
 }  // namespace blink