Backend for css rule tracking

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

Index: third_party/WebKit/Source/core/dom/StyleEngine.h
diff --git a/third_party/WebKit/Source/core/dom/StyleEngine.h b/third_party/WebKit/Source/core/dom/StyleEngine.h
index 32145eb61a1b556bc49a1287c94b064164576a6c..49ffadae5c8be142695153247023e4854865f6ea 100644
--- a/third_party/WebKit/Source/core/dom/StyleEngine.h
+++ b/third_party/WebKit/Source/core/dom/StyleEngine.h
@@ -57,6 +57,7 @@ class Node;
 class RuleFeatureSet;
 class ShadowTreeStyleSheetCollection;
 class StyleRuleFontFace;
+class StyleRuleUsageTracker;
 class StyleSheet;
 class StyleSheetContents;
 class ViewportStyleResolver;
@@ -165,6 +166,8 @@ class CORE_EXPORT StyleEngine final
   }
   void resetAuthorStyle(TreeScope&);
 
+  void setRuleUsageTracker(StyleRuleUsageTracker*);
+
   StyleResolver* resolver() const { return m_resolver.get(); }
 
   StyleResolver& ensureResolver() {
@@ -299,6 +302,8 @@ class CORE_EXPORT StyleEngine final
   HeapVector<Member<CSSStyleSheet>> m_injectedAuthorStyleSheets;
   Member<CSSStyleSheet> m_inspectorStyleSheet;
 
+  Member<StyleRuleUsageTracker> m_tracker;
+
   Member<DocumentStyleSheetCollection> m_documentStyleSheetCollection;
 
   typedef HeapHashMap<WeakMember<TreeScope>,