Using the new webkit CSS change notification instead of a mutation observer.

chrome/renderer/extensions/dispatcher.h

Index: chrome/renderer/extensions/dispatcher.h
diff --git a/chrome/renderer/extensions/dispatcher.h b/chrome/renderer/extensions/dispatcher.h
index a3a5275d491759a02295cf8898f9637b98bfc30f..5dc86963f27408b2767f38d069900395e4993310 100644
--- a/chrome/renderer/extensions/dispatcher.h
+++ b/chrome/renderer/extensions/dispatcher.h
@@ -19,6 +19,7 @@
 #include "chrome/renderer/extensions/v8_schema_registry.h"
 #include "chrome/renderer/resource_bundle_source_map.h"
 #include "extensions/common/event_filter.h"
+#include "third_party/WebKit/Source/Platform/chromium/public/WebVector.h"
 #include "v8/include/v8.h"
 
 class GURL;
@@ -101,6 +102,11 @@ class Dispatcher : public content::RenderProcessObserver {
 
   void DidCreateDocumentElement(WebKit::WebFrame* frame);
 
+  void CssMatches(
+      WebKit::WebFrame* frame,
+      const WebKit::WebVector<WebKit::WebString>& newlyMatchingSelectors,
+      const WebKit::WebVector<WebKit::WebString>& stoppedMatchingSelectors);
+
   // TODO(mpcomplete): remove. http://crbug.com/100411
   bool IsAdblockWithWebRequestInstalled() const {
     return webrequest_adblock_;