Backend for css rule tracking

third_party/WebKit/Source/core/inspector/InspectorDOMAgent.h

Index: third_party/WebKit/Source/core/inspector/InspectorDOMAgent.h
diff --git a/third_party/WebKit/Source/core/inspector/InspectorDOMAgent.h b/third_party/WebKit/Source/core/inspector/InspectorDOMAgent.h
index e2771ddde87cd84330a1886822b0837869aadd69..96488e65140eb2024803516d183d7c899b0959b0 100644
--- a/third_party/WebKit/Source/core/inspector/InspectorDOMAgent.h
+++ b/third_party/WebKit/Source/core/inspector/InspectorDOMAgent.h
@@ -71,6 +71,7 @@ class CORE_EXPORT InspectorDOMAgent final
  public:
   struct CORE_EXPORT DOMListener : public GarbageCollectedMixin {
     virtual ~DOMListener() {}
+    virtual void didAddDocument(Document*) = 0;
     virtual void didRemoveDocument(Document*) = 0;
     virtual void didRemoveDOMNode(Node*) = 0;
     virtual void didModifyDOMAttr(Element*) = 0;