Backend for css rule tracking

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

Index: third_party/WebKit/Source/core/dom/StyleEngine.cpp
diff --git a/third_party/WebKit/Source/core/dom/StyleEngine.cpp b/third_party/WebKit/Source/core/dom/StyleEngine.cpp
index 2c1ab5550ef6c6a909628ea901a1c6758c288845..13438bb637caa025d62107e23809657c1b50680f 100644
--- a/third_party/WebKit/Source/core/dom/StyleEngine.cpp
+++ b/third_party/WebKit/Source/core/dom/StyleEngine.cpp
@@ -37,6 +37,7 @@
 #include "core/css/StyleSheetContents.h"
 #include "core/css/invalidation/InvalidationSet.h"
 #include "core/css/resolver/ScopedStyleResolver.h"
+#include "core/css/resolver/StyleRuleUsageTracker.h"
 #include "core/css/resolver/ViewportStyleResolver.h"
 #include "core/dom/DocumentStyleSheetCollector.h"
 #include "core/dom/Element.h"
@@ -432,9 +433,18 @@ void StyleEngine::appendActiveAuthorStyleSheets() {
   m_resolver->finishAppendAuthorStyleSheets();
 }
 
+void StyleEngine::setRuleUsageTracker(Member<StyleRuleUsageTracker> tracker) {
+  m_tracker = tracker;
+
+  if (m_tracker && m_resolver)
+    m_resolver->setRuleUsageTracker(m_tracker);
+}
+
 void StyleEngine::createResolver() {
   m_resolver = StyleResolver::create(*m_document);
 
+  m_resolver->setRuleUsageTracker(m_tracker);
+
   // A scoped style resolver for document will be created during
   // appendActiveAuthorStyleSheets if needed.
   appendActiveAuthorStyleSheets();
@@ -1014,6 +1024,7 @@ DEFINE_TRACE(StyleEngine) {
   visitor->trace(m_fontSelector);
   visitor->trace(m_textToSheetCache);
   visitor->trace(m_sheetToTextCache);
+  visitor->trace(m_tracker);
   CSSFontSelectorClient::trace(visitor);
 }