Change CSSParserContext to have a Document handle (vs UseCounter).

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 21 matching lines @@
 #include "core/dom/StyleEngine.h"
 #include "core/frame/UseCounter.h"
 #include "core/inspector/InspectorTraceEvents.h"
 #include "core/loader/resource/CSSStyleSheetResource.h"
 #include "platform/Histogram.h"
 #include "platform/instrumentation/tracing/TraceEvent.h"
 #include "platform/weborigin/SecurityOrigin.h"
 
 namespace blink {
 
+// static
+const Document* StyleSheetContents::singleOwnerDocument(
+    const StyleSheetContents* styleSheetContents) {
+  // FIXME(https://crbug.com/242125): We may want to handle stylesheets that

[haraken, 2017/02/09 02:01:42]

TODO

[Bret, 2017/02/09 02:08:18]

Done.

+  // have multiple owners when this is used for UseCounter.
+  if (styleSheetContents && styleSheetContents->hasSingleOwnerNode())
+    return styleSheetContents->singleOwnerDocument();
+  return nullptr;
+}
+
 // Rough size estimate for the memory cache.
 unsigned StyleSheetContents::estimatedSizeInBytes() const {
   // Note that this does not take into account size of the strings hanging from
   // various objects. The assumption is that nearly all of of them are atomic
   // and would exist anyway.
   unsigned size = sizeof(*this);
 
   // FIXME: This ignores the children of media rules.
   // Most rules are StyleRules.
   size += ruleCount() * StyleRule::averageSizeInBytes();
@@ skipping 640 matching lines @@
   visitor->trace(m_namespaceRules);
   visitor->trace(m_childRules);
   visitor->trace(m_loadingClients);
   visitor->trace(m_completedClients);
   visitor->trace(m_ruleSet);
   visitor->trace(m_referencedFromResource);
   visitor->trace(m_parserContext);
 }
 
 }  // namespace blink