Removed unused StyleEngine::didRemoveShadowRoot().

third_party/WebKit/Source/core/dom/StyleEngine.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2011, 2012 Apple Inc. All
  * rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved.
  * (http://www.torchmobile.com/)
  * Copyright (C) 2008, 2009, 2011, 2012 Google Inc. All rights reserved.
@@ skipping 355 matching lines @@
             m_styleSheetCollectionMap.get(treeScope))
       activeStyleSheets.appendVector(collection->activeAuthorStyleSheets());
   }
 
   // FIXME: Inspector needs a vector which has all active stylesheets.
   // However, creating such a large vector might cause performance regression.
   // Need to implement some smarter solution.
   return activeStyleSheets;
 }
 
-void StyleEngine::didRemoveShadowRoot(ShadowRoot* shadowRoot) {
-  m_styleSheetCollectionMap.remove(shadowRoot);
-  m_activeTreeScopes.remove(shadowRoot);
-  m_dirtyTreeScopes.remove(shadowRoot);
-}
-
 void StyleEngine::shadowRootRemovedFromDocument(ShadowRoot* shadowRoot) {
   if (StyleResolver* styleResolver = resolver()) {
     styleResolver->resetRuleFeatures();
 
     if (TreeScopeStyleSheetCollection* collection =
             styleSheetCollectionFor(*shadowRoot))
       styleResolver->removePendingAuthorStyleSheets(
           collection->activeAuthorStyleSheets());
   }
   shadowRoot->clearScopedStyleResolver();
@@ skipping 46 matching lines @@
   // A scoped style resolver for document will be created during
   // appendActiveAuthorStyleSheets if needed.
   appendActiveAuthorStyleSheets();
 }
 
 void StyleEngine::clearResolver() {
   DCHECK(!document().inStyleRecalc());
   DCHECK(isMaster() || !m_resolver);
 
   document().clearScopedStyleResolver();
-  // StyleEngine::shadowRootRemovedFromDocument removes not-in-document
-  // treescopes from activeTreeScopes. StyleEngine::didRemoveShadowRoot
-  // removes treescopes which are being destroyed from activeTreeScopes.
-  // So we need to clearScopedStyleResolver for treescopes which have been
-  // just removed from document. If document is destroyed before invoking
-  // updateActiveStyleSheets, the treescope has a scopedStyleResolver which
-  // has destroyed StyleSheetContents.
+  // TODO(rune@opera.com): The clearing of all shadow tree scoped style
+  // resolvers below should not be necessary. It was introduced to fix a crash
+  // bug (https://crbug.com/447976) when clearResolver is called from didDetach
+  // on document destruction. That was pre-oilpan, and removing the for-loop
+  // below does not re-introduce that crash. If m_activeTreeScopes keeps too
+  // much memory alive after detach, we should probably clear m_activeTreeScopes
+  // in didDetach instead.
+  //
+  // The current code will clear too much if clearResolver is called from
+  // clearMasterResolver as a result of a Reconstruct in
+  // DocumentStyleSheetCollection. Such a reconstruct should not necessarily
+  // affect scoped resolvers from shadow trees at all.
   for (TreeScope* treeScope : m_activeTreeScopes)
     treeScope->clearScopedStyleResolver();
 
   m_treeBoundaryCrossingScopes.clear();
 
   if (m_resolver) {
     TRACE_EVENT1("blink", "StyleEngine::clearResolver", "frame",
                  document().frame());
     m_resolver->dispose();
     m_resolver.clear();
@@ skipping 555 matching lines @@
 }
 
 DEFINE_TRACE_WRAPPERS(StyleEngine) {
   for (auto sheet : m_injectedAuthorStyleSheets) {
     visitor->traceWrappers(sheet);
   }
   visitor->traceWrappers(m_documentStyleSheetCollection);
 }
 
 }  // namespace blink