Backend for css rule tracking

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

Index: third_party/WebKit/Source/core/css/resolver/StyleResolver.cpp
diff --git a/third_party/WebKit/Source/core/css/resolver/StyleResolver.cpp b/third_party/WebKit/Source/core/css/resolver/StyleResolver.cpp
index f8b451a9ae24d3de8a09fec0994cd2134cf69783..acf81afa2f1bb5941dec4c16595b61e10f55fae7 100644
--- a/third_party/WebKit/Source/core/css/resolver/StyleResolver.cpp
+++ b/third_party/WebKit/Source/core/css/resolver/StyleResolver.cpp
@@ -214,6 +214,10 @@ void StyleResolver::initWatchedSelectorRules() {
                                           RuleHasNoSpecialState);
 }
 
+void StyleResolver::setRuleUsageTracker(StyleRuleUsageTracker* tracker) {
+  m_tracker = tracker;
+}
+
 void StyleResolver::lazyAppendAuthorStyleSheets(
     unsigned firstNew,
     const HeapVector<Member<CSSStyleSheet>>& styleSheets) {
@@ -846,6 +850,8 @@ PassRefPtr<ComputedStyle> StyleResolver::styleForElement(
       }
     }
 
+    addMatchedRulesToTracker(collector);
+
     if (element->computedStyle() &&
         element->computedStyle()->textAutosizingMultiplier() !=
             state.style()->textAutosizingMultiplier()) {
@@ -1020,6 +1026,8 @@ bool StyleResolver::pseudoStyleForElementInternal(
     matchAuthorRules(*state.element(), collector);
     collector.finishAddingAuthorRulesForTreeScope();
 
+    addMatchedRulesToTracker(collector);
+
     if (!collector.matchedResult().hasMatchedProperties())
       return false;
 
@@ -1142,6 +1150,14 @@ void StyleResolver::updateFont(StyleResolverState& state) {
   state.setConversionZoom(state.style()->effectiveZoom());
 }
 
+void StyleResolver::addMatchedRulesToTracker(ElementRuleCollector& collector) {
+  if (!m_tracker)
+    return;
+
+  for (auto matchedRule : collector.matchedRulesList())
+    m_tracker->markRuleAsUsed(matchedRule.ruleData()->rule());
+}
+
 StyleRuleList* StyleResolver::styleRulesForElement(Element* element,
                                                    unsigned rulesToInclude) {
   ASSERT(element);
@@ -1163,6 +1179,8 @@ CSSRuleList* StyleResolver::pseudoCSSRulesForElement(Element* element,
                                  state.style());
   collector.setMode(SelectorChecker::CollectingCSSRules);
   collectPseudoRulesForElement(*element, collector, pseudoId, rulesToInclude);
+
+  addMatchedRulesToTracker(collector);
   return collector.matchedCSSRuleList();
 }
 
@@ -1851,6 +1869,8 @@ void StyleResolver::applyCallbackSelectors(StyleResolverState& state) {
   collector.collectMatchingRules(matchRequest);
   collector.sortAndTransferMatchedRules();
 
+  addMatchedRulesToTracker(collector);
+
   StyleRuleList* rules = collector.matchedStyleRuleList();
   if (!rules)
     return;
@@ -1922,6 +1942,7 @@ DEFINE_TRACE(StyleResolver) {
   visitor->trace(m_styleSharingLists);
   visitor->trace(m_pendingStyleSheets);
   visitor->trace(m_document);
+  visitor->trace(m_tracker);
 }
 
 }  // namespace blink