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

chrome/renderer/resources/extensions/content_watcher.js

Index: chrome/renderer/resources/extensions/content_watcher.js
diff --git a/chrome/renderer/resources/extensions/content_watcher.js b/chrome/renderer/resources/extensions/content_watcher.js
index 4854f8cd3369b8fb939f60101fb370c18a84aac8..a05145d2cf3f9f2661ec910379232ee4bd16d27f 100644
--- a/chrome/renderer/resources/extensions/content_watcher.js
+++ b/chrome/renderer/resources/extensions/content_watcher.js
@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-var contentWatcherNative = requireNative("contentWatcherNative");
-
 // Returns the indices in |css_selectors| that match any element on the page.
 exports.FindMatchingSelectors = function(css_selectors) {
   var result = []
@@ -18,15 +16,3 @@ exports.FindMatchingSelectors = function(css_selectors) {
   });
   return result;
 };
-
-// Watches the page for all changes and calls FrameMutated (a C++ callback) in
-// response.
-var mutation_observer = new WebKitMutationObserver(
-  contentWatcherNative.FrameMutated);
-
-// This runs once per frame, when the module is 'require'd.
-mutation_observer.observe(document, {
-  childList: true,
-  attributes: true,
-  characterData: true,
-  subtree: true});