[LazyParseCSS] Ensure UseCounting has parity with strict parsing

third_party/WebKit/Source/core/css/StyleSheetContents.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 308 matching lines @@
 }
 
 const AtomicString& StyleSheetContents::namespaceURIFromPrefix(
     const AtomicString& prefix) {
   return m_namespaces.get(prefix);
 }
 
 void StyleSheetContents::parseAuthorStyleSheet(
     const CSSStyleSheetResource* cachedStyleSheet,
     const SecurityOrigin* securityOrigin) {
+  // All StyleSheetContents are first parsed with a single owner document and
+  // node. This guarantees us that we will always have a valid document for use
+  // counting.
+  DCHECK(hasSingleOwnerDocument());
+  DCHECK(hasSingleOwnerNode());
+
   TRACE_EVENT1("blink,devtools.timeline", "ParseAuthorStyleSheet", "data",
                InspectorParseAuthorStyleSheetEvent::data(cachedStyleSheet));
   double startTimeMS = monotonicallyIncreasingTimeMS();
 
   bool isSameOriginRequest =
       securityOrigin && securityOrigin->canRequest(baseURL());
 
   // When the response was fetched via the Service Worker, the original URL may
   // not be same as the base URL.
   // TODO(horo): When we will use the original URL as the base URL, we can
@@ skipping 145 matching lines @@
   if (root->m_loadingClients.size())
     return (*root->m_loadingClients.begin())->ownerNode();
   return (*root->m_completedClients.begin())->ownerNode();
 }
 
 Document* StyleSheetContents::singleOwnerDocument() const {
   StyleSheetContents* root = rootStyleSheet();
   return root->clientSingleOwnerDocument();
 }
 
+Document* StyleSheetContents::anyOwnerDocument() const {
+  return rootStyleSheet()->clientAnyOwnerDocument();
+}
+
 static bool childRulesHaveFailedOrCanceledSubresources(
     const HeapVector<Member<StyleRuleBase>>& rules) {
   for (unsigned i = 0; i < rules.size(); ++i) {
     const StyleRuleBase* rule = rules[i].get();
     switch (rule->type()) {
       case StyleRuleBase::Style:
         if (toStyleRule(rule)->propertiesHaveFailedOrCanceledSubresources())
           return true;
         break;
       case StyleRuleBase::FontFace:
@@ skipping 20 matching lines @@
     }
   }
   return false;
 }
 
 bool StyleSheetContents::hasFailedOrCanceledSubresources() const {
   ASSERT(isCacheableForResource());
   return childRulesHaveFailedOrCanceledSubresources(m_childRules);
 }
 
+Document* StyleSheetContents::clientAnyOwnerDocument() const {
+  if (clientSize() <= 0)
+    return nullptr;
+  return m_loadingClients.size()
+             ? (*m_loadingClients.begin())->ownerDocument()
+             : (*m_completedClients.begin())->ownerDocument();

[rune, 2016/12/02 22:18:08]

Nit: is the return rewrite due to the chromium coding style? I think it was more
readable before.

[Charlie Harrison, 2016/12/02 22:38:46]

I can change it back, I was mostly just trying to remove a branch.

[Charlie Harrison, 2016/12/05 19:30:09]

Done.

+}
+
 Document* StyleSheetContents::clientSingleOwnerDocument() const {
-  if (!m_hasSingleOwnerDocument || clientSize() <= 0)
-    return nullptr;
-
-  if (m_loadingClients.size())
-    return (*m_loadingClients.begin())->ownerDocument();
-  return (*m_completedClients.begin())->ownerDocument();
+  return m_hasSingleOwnerDocument ? clientAnyOwnerDocument() : nullptr;
 }
 
 StyleSheetContents* StyleSheetContents::parentStyleSheet() const {
   return m_ownerRule ? m_ownerRule->parentStyleSheet() : nullptr;
 }
 
 void StyleSheetContents::registerClient(CSSStyleSheet* sheet) {
   ASSERT(!m_loadingClients.contains(sheet) &&
          !m_completedClients.contains(sheet));
 
@@ skipping 134 matching lines @@
   visitor->trace(m_importRules);
   visitor->trace(m_namespaceRules);
   visitor->trace(m_childRules);
   visitor->trace(m_loadingClients);
   visitor->trace(m_completedClients);
   visitor->trace(m_ruleSet);
   visitor->trace(m_referencedFromResource);
 }
 
 }  // namespace blink