Oilpan: promptly dispose style resolvers upon clearing.

third_party/WebKit/Source/core/css/resolver/ScopedStyleResolver.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 28 matching lines @@
 #include "core/css/resolver/ViewportStyleResolver.h"
 #include "core/dom/Document.h"
 #include "core/dom/StyleEngine.h"
 #include "core/dom/shadow/ElementShadow.h"
 #include "core/dom/shadow/ShadowRoot.h"
 #include "core/html/HTMLStyleElement.h"
 #include "core/svg/SVGStyleElement.h"
 
 namespace blink {
 
+void ScopedStyleResolver::dispose()
+{
+    m_keyframesRuleMap.clear();
+
+    if (m_treeBoundaryCrossingRuleSet) {
+        for (size_t i = 0; i < m_treeBoundaryCrossingRuleSet->size(); ++i) {
+            if (RuleSet* ruleSet = m_treeBoundaryCrossingRuleSet->at(i)->m_ruleSet.get())
+                ruleSet->dispose();
+        }
+
+        m_treeBoundaryCrossingRuleSet->clear();
+        m_treeBoundaryCrossingRuleSet.clear();
+    }
+
+}
+
 ScopedStyleResolver* ScopedStyleResolver::parent() const
 {
     for (TreeScope* scope = treeScope().parentTreeScope(); scope; scope = scope->parentTreeScope()) {
         if (ScopedStyleResolver* resolver = scope->scopedStyleResolver())
             return resolver;
     }
     return nullptr;
 }
 
 void ScopedStyleResolver::addKeyframeRules(const RuleSet& ruleSet)
 {
     const WillBeHeapVector<RawPtrWillBeMember<StyleRuleKeyframes>> keyframesRules = ruleSet.keyframesRules();
     for (unsigned i = 0; i < keyframesRules.size(); ++i)
         addKeyframeStyle(keyframesRules[i]);
 }
 
 void ScopedStyleResolver::addFontFaceRules(const RuleSet& ruleSet)
 {
     // FIXME(BUG 72461): We don't add @font-face rules of scoped style sheets for the moment.
     if (!treeScope().rootNode().isDocumentNode())
         return;
 
     Document& document = treeScope().document();
     CSSFontSelector* cssFontSelector = document.styleEngine().fontSelector();
     const WillBeHeapVector<RawPtrWillBeMember<StyleRuleFontFace>> fontFaceRules = ruleSet.fontFaceRules();
+    if (!fontFaceRules.size())
+        return;
     for (auto& fontFaceRule : fontFaceRules) {
         if (RefPtrWillBeRawPtr<FontFace> fontFace = FontFace::create(&document, fontFaceRule))
             cssFontSelector->fontFaceCache()->add(cssFontSelector, fontFaceRule, fontFace);
     }
-    if (fontFaceRules.size())
-        document.styleResolver()->invalidateMatchedPropertiesCache();
+    document.styleResolver()->invalidateMatchedPropertiesCache();
 }
 
 void ScopedStyleResolver::appendCSSStyleSheet(CSSStyleSheet& cssSheet, const MediaQueryEvaluator& medium)
 {
     unsigned index = m_authorStyleSheets.size();
     m_authorStyleSheets.append(&cssSheet);
     StyleSheetContents* sheet = cssSheet.contents();
     AddRuleFlags addRuleFlags = treeScope().document().securityOrigin()->canRequest(sheet->baseURL()) ? RuleHasDocumentSecurityOrigin : RuleHasNoSpecialState;
     const RuleSet& ruleSet = sheet->ensureRuleSet(medium, addRuleFlags);
 
@@ skipping 139 matching lines @@
     m_treeBoundaryCrossingRuleSet->append(RuleSubSet::create(parentStyleSheet, sheetIndex, ruleSetForScope.release()));
 }
 
 DEFINE_TRACE(ScopedStyleResolver::RuleSubSet)
 {
     visitor->trace(m_parentStyleSheet);
     visitor->trace(m_ruleSet);
 }
 
 } // namespace blink