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

chrome/renderer/extensions/extension_helper.cc

Index: chrome/renderer/extensions/extension_helper.cc
diff --git a/chrome/renderer/extensions/extension_helper.cc b/chrome/renderer/extensions/extension_helper.cc
index c97c22a239fa6c1eb88211b4be1d8f9a75ea20b6..0e6c0070b56df617118b677cc5d804e50fcf6b99 100644
--- a/chrome/renderer/extensions/extension_helper.cc
+++ b/chrome/renderer/extensions/extension_helper.cc
@@ -17,6 +17,7 @@
 #include "chrome/common/url_constants.h"
 #include "chrome/common/view_type.h"
 #include "chrome/renderer/extensions/chrome_v8_context.h"
+#include "chrome/renderer/extensions/content_watcher.h"
 #include "chrome/renderer/extensions/dispatcher.h"
 #include "chrome/renderer/extensions/miscellaneous_bindings.h"
 #include "chrome/renderer/extensions/user_script_scheduler.h"
@@ -151,6 +152,7 @@ ExtensionHelper::ExtensionHelper(content::RenderView* render_view,
       view_type_(chrome::VIEW_TYPE_INVALID),
       tab_id_(-1),
       browser_window_id_(-1) {
+  dispatcher_->content_watcher()->OnWebViewCreated(render_view->GetWebView());
 }
 
 ExtensionHelper::~ExtensionHelper() {
@@ -284,6 +286,14 @@ void ExtensionHelper::FrameDetached(WebFrame* frame) {
   g_schedulers.Get().erase(i);
 }
 
+void ExtensionHelper::CssMatches(
+    WebKit::WebFrame* frame,
+    const WebKit::WebVector<WebKit::WebString>& newlyMatchingSelectors,
+    const WebKit::WebVector<WebKit::WebString>& stoppedMatchingSelectors) {
+  dispatcher_->CssMatches(frame, newlyMatchingSelectors,
+                          stoppedMatchingSelectors);
+}
+
 void ExtensionHelper::DidCreateDataSource(WebFrame* frame, WebDataSource* ds) {
   // If there are any app-related fetches in progress, they can be cancelled now
   // since we have navigated away from the page that created them.