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

content/renderer/render_view_impl.cc

Index: content/renderer/render_view_impl.cc
diff --git a/content/renderer/render_view_impl.cc b/content/renderer/render_view_impl.cc
index ce8cb51b2de58f8d9bc45791875d416db8f9d79b..a4fe2c3ff01dcca62ca894865c5cee0ffedf2ee3 100644
--- a/content/renderer/render_view_impl.cc
+++ b/content/renderer/render_view_impl.cc
@@ -2865,6 +2865,15 @@ void RenderViewImpl::didChangeName(WebFrame* frame,
                                        UTF16ToUTF8(name)));
 }
 
+void RenderViewImpl::cssMatches(
+    WebFrame* frame,
+    const WebVector<WebString>& newlyMatchingSelectors,
+    const WebVector<WebString>& stoppedMatchingSelectors) {
+  FOR_EACH_OBSERVER(
+      RenderViewObserver, observers_,
+      CssMatches(frame, newlyMatchingSelectors, stoppedMatchingSelectors));
+}
+
 void RenderViewImpl::loadURLExternally(
     WebFrame* frame, const WebURLRequest& request,
     WebNavigationPolicy policy) {