Storage of ComputedStyle separate from LayoutObject.

third_party/WebKit/Source/core/dom/NodeComputedStyle.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2008 David Smith (catfish.man@gmail.com)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 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.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Library General Public License for more details.
  *
  * You should have received a copy of the GNU Library General Public License
  * along with this library; see the file COPYING.LIB.  If not, write to
  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  *
  */
 
 #ifndef NodeComputedStyle_h
 #define NodeComputedStyle_h
 
 #include "core/dom/LayoutTreeBuilderTraversal.h"
 #include "core/dom/Node.h"
+#include "core/dom/NodeRareData.h"
 #include "core/dom/shadow/InsertionPoint.h"
 #include "core/html/HTMLOptGroupElement.h"
 #include "core/layout/LayoutObject.h"
 #include "core/style/ComputedStyle.h"
 
 namespace blink {
 
 inline const ComputedStyle* Node::computedStyle() const
 {
     return mutableComputedStyle();
 }
 
 inline ComputedStyle* Node::mutableComputedStyle() const
 {
-    if (LayoutObject* layoutObject = this->layoutObject())
-        return layoutObject->mutableStyle();
+    if (hasLayoutObject())
+        return layoutObject()->mutableStyle();
     // <option> and <optgroup> can be styled even if they don't get layout objects,
     // so they store their style internally and return it through nonLayoutObjectComputedStyle().
     // We check here explicitly to avoid the virtual call in the common case.
     if (isHTMLOptGroupElement(*this) || isHTMLOptionElement(this))
         return nonLayoutObjectComputedStyle();
-    return 0;
+    if (hasRareData())
+        return rareData()->computedStyle();
+    return m_data.m_computedStyle;
+}
+
+inline void Node::setComputedStyle(ComputedStyle* computedStyle)

[Timothy Loh, 2016/06/01 07:36:38]

should take PassRefPtr<ComputedStyle>

+{
+    if (hasRareData()) {
+        rareData()->setComputedStyle(computedStyle);
+    } else if (hasLayoutObject()) {
+        m_data.m_layoutObject->setStyleInternal(computedStyle);
+    } else {
+        if (computedStyle)
+            computedStyle->ref();
+        if (m_data.m_computedStyle)
+            m_data.m_computedStyle->deref();
+        m_data.m_computedStyle = computedStyle;
+    }
 }
 
 inline const ComputedStyle* Node::parentComputedStyle() const
 {
     if (isSlotOrActiveInsertionPoint())
         return 0;
     ContainerNode* parent = LayoutTreeBuilderTraversal::parent(*this);
     return parent ? parent->computedStyle() : 0;
 }
 
 inline const ComputedStyle& Node::computedStyleRef() const
 {
     const ComputedStyle* style = computedStyle();
     DCHECK(style);
     return *style;
 }
 
 } // namespace blink
 #endif // NodeComputedStyle_h