Make stylesheet owner node a reference instead of pointer.

third_party/WebKit/Source/core/css/CSSStyleSheet.cpp

 /*
  * (C) 1999-2003 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2004, 2006, 2007, 2012 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,
@@ skipping 51 matching lines @@
 
     unsigned length() const override { return m_styleSheet->length(); }
     CSSRule* item(unsigned index) const override { return m_styleSheet->item(index); }
 
     CSSStyleSheet* styleSheet() const override { return m_styleSheet; }
 
     Member<CSSStyleSheet> m_styleSheet;
 };
 
 #if DCHECK_IS_ON()
-static bool isAcceptableCSSStyleSheetParent(Node* parentNode)
+static bool isAcceptableCSSStyleSheetParent(const Node& parentNode)
 {
     // Only these nodes can be parents of StyleSheets, and they need to call
     // clearOwnerNode() when moved out of document. Note that destructor of
     // the nodes don't call clearOwnerNode() with Oilpan.
-    return !parentNode
-        || parentNode->isDocumentNode()
-        || isHTMLLinkElement(*parentNode)
-        || isHTMLStyleElement(*parentNode)
-        || isSVGStyleElement(*parentNode)
-        || parentNode->getNodeType() == Node::kProcessingInstructionNode;
+    return parentNode.isDocumentNode()
+        || isHTMLLinkElement(parentNode)
+        || isHTMLStyleElement(parentNode)
+        || isSVGStyleElement(parentNode)
+        || parentNode.getNodeType() == Node::kProcessingInstructionNode;
 }
 #endif
 
 CSSStyleSheet* CSSStyleSheet::create(StyleSheetContents* sheet, CSSImportRule* ownerRule)
 {
     return new CSSStyleSheet(sheet, ownerRule);
 }
 
-CSSStyleSheet* CSSStyleSheet::create(StyleSheetContents* sheet, Node* ownerNode)
+CSSStyleSheet* CSSStyleSheet::create(StyleSheetContents* sheet, Node& ownerNode)
 {
     return new CSSStyleSheet(sheet, ownerNode, false, TextPosition::minimumPosition());
 }
 
-CSSStyleSheet* CSSStyleSheet::createInline(StyleSheetContents* sheet, Node* ownerNode, const TextPosition& startPosition)
+CSSStyleSheet* CSSStyleSheet::createInline(StyleSheetContents* sheet, Node& ownerNode, const TextPosition& startPosition)
 {
     DCHECK(sheet);
     return new CSSStyleSheet(sheet, ownerNode, true, startPosition);
 }
 
-CSSStyleSheet* CSSStyleSheet::createInline(Node* ownerNode, const KURL& baseURL, const TextPosition& startPosition, const String& encoding)
+CSSStyleSheet* CSSStyleSheet::createInline(Node& ownerNode, const KURL& baseURL, const TextPosition& startPosition, const String& encoding)
 {
-    CSSParserContext parserContext(ownerNode->document(), nullptr, baseURL, encoding);
+    CSSParserContext parserContext(ownerNode.document(), nullptr, baseURL, encoding);
     StyleSheetContents* sheet = StyleSheetContents::create(baseURL.getString(), parserContext);
     return new CSSStyleSheet(sheet, ownerNode, true, startPosition);
 }
 
 CSSStyleSheet::CSSStyleSheet(StyleSheetContents* contents, CSSImportRule* ownerRule)
     : m_contents(contents)
     , m_isInlineStylesheet(false)
     , m_isDisabled(false)
     , m_ownerNode(nullptr)
     , m_ownerRule(ownerRule)
     , m_startPosition(TextPosition::minimumPosition())
     , m_loadCompleted(false)
 {
     m_contents->registerClient(this);
 }
 
-CSSStyleSheet::CSSStyleSheet(StyleSheetContents* contents, Node* ownerNode, bool isInlineStylesheet, const TextPosition& startPosition)
+CSSStyleSheet::CSSStyleSheet(StyleSheetContents* contents, Node& ownerNode, bool isInlineStylesheet, const TextPosition& startPosition)
     : m_contents(contents)
     , m_isInlineStylesheet(isInlineStylesheet)
     , m_isDisabled(false)
-    , m_ownerNode(ownerNode)
+    , m_ownerNode(&ownerNode)

[sashab, 2016/09/21 01:33:29]

Might be a stretch but... Can we make m_ownerNode a reference too? Or do we need
m_ownerNode to be a Member<> for lifecycle reasons?

[rune, 2016/09/21 07:17:45]

m_ownerNode is nullptr for @import stylesheets. It will also be null if the
stylesheet is referenced from a script, but the link/style element for the sheet
is removed from the dom.

     , m_ownerRule(nullptr)
     , m_startPosition(startPosition)
     , m_loadCompleted(false)
 {
 #if DCHECK_IS_ON()
     DCHECK(isAcceptableCSSStyleSheetParent(ownerNode));
 #endif
     m_contents->registerClient(this);
 }
 
@@ skipping 294 matching lines @@
     visitor->trace(m_mediaQueries);
     visitor->trace(m_ownerNode);
     visitor->trace(m_ownerRule);
     visitor->trace(m_mediaCSSOMWrapper);
     visitor->trace(m_childRuleCSSOMWrappers);
     visitor->trace(m_ruleListCSSOMWrapper);
     StyleSheet::trace(visitor);
 }
 
 } // namespace blink