Backend for css rule tracking

third_party/WebKit/Source/core/css/ElementRuleCollector.h

Index: third_party/WebKit/Source/core/css/ElementRuleCollector.h
diff --git a/third_party/WebKit/Source/core/css/ElementRuleCollector.h b/third_party/WebKit/Source/core/css/ElementRuleCollector.h
index a33d09b4443450f0f6b7d546d020e79bacfe1ce2..56ecc8e239b03ce52190342152a20637b00001ed 100644
--- a/third_party/WebKit/Source/core/css/ElementRuleCollector.h
+++ b/third_party/WebKit/Source/core/css/ElementRuleCollector.h
@@ -143,6 +143,10 @@ class ElementRuleCollector {
     return m_pseudoStyleRequest.pseudoId != PseudoIdNone;
   }
 
+  const HeapVector<MatchedRule, 32>& matchedRulesList() const {

[pfeldman, 2016/11/03 21:23:30]

I don't think you should expose otherwise encapsulated list. There is a better
alternative:

void reportUsage(Tracker tracker)

+    return m_matchedRules;
+  }
+
  private:
   template <typename RuleDataListType>
   void collectMatchingRulesForList(const RuleDataListType*,