Use Blink support to watch CSS selectors directly instead of using a MutationObserver.

content/renderer/render_frame_impl.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_RENDERER_RENDER_FRAME_IMPL_H_
 #define CONTENT_RENDERER_RENDER_FRAME_IMPL_H_
 
 #include "base/basictypes.h"
 #include "content/public/renderer/render_frame.h"
 #include "ipc/ipc_message.h"
@@ skipping 43 matching lines @@
       WebKit::WebApplicationCacheHostClient* client);
   virtual WebKit::WebCookieJar* cookieJar(WebKit::WebFrame* frame);
   virtual void didAccessInitialDocument(WebKit::WebFrame* frame);
   virtual void didCreateFrame(WebKit::WebFrame* parent,
                               WebKit::WebFrame* child);
   virtual void didDisownOpener(WebKit::WebFrame* frame);
   virtual void frameDetached(WebKit::WebFrame* frame);
   virtual void willClose(WebKit::WebFrame* frame);
   virtual void didChangeName(WebKit::WebFrame* frame,
                              const WebKit::WebString& name);
+  virtual void didMatchCSS(
+      WebKit::WebFrame* frame,
+      const WebKit::WebVector<WebKit::WebString>& newly_matching_selectors,
+      const WebKit::WebVector<WebKit::WebString>& stopped_matching_selectors);
   virtual void loadURLExternally(WebKit::WebFrame* frame,
                                  const WebKit::WebURLRequest& request,
                                  WebKit::WebNavigationPolicy policy);
   virtual void loadURLExternally(
       WebKit::WebFrame* frame,
       const WebKit::WebURLRequest& request,
       WebKit::WebNavigationPolicy policy,
       const WebKit::WebString& suggested_name);
   virtual WebKit::WebNavigationPolicy decidePolicyForNavigation(
       WebKit::WebFrame* frame,
@@ skipping 113 matching lines @@
   int routing_id_;
   bool is_swapped_out_;
   bool is_detaching_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderFrameImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_RENDER_FRAME_IMPL_H_