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

chrome/renderer/extensions/dispatcher.h

 // Copyright (c) 2012 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 CHROME_RENDERER_EXTENSIONS_DISPATCHER_H_
 #define CHROME_RENDERER_EXTENSIONS_DISPATCHER_H_
 
 #include <map>
 #include <set>
 #include <string>
 #include <vector>
 
 #include "base/memory/shared_memory.h"
 #include "base/timer/timer.h"
 #include "chrome/common/extensions/extension_set.h"
 #include "chrome/renderer/extensions/chrome_v8_context.h"
 #include "chrome/renderer/extensions/chrome_v8_context_set.h"
 #include "chrome/renderer/extensions/v8_schema_registry.h"
 #include "chrome/renderer/resource_bundle_source_map.h"
 #include "content/public/renderer/render_process_observer.h"
 #include "extensions/common/event_filter.h"
 #include "extensions/common/features/feature.h"
+#include "third_party/WebKit/public/platform/WebString.h"
+#include "third_party/WebKit/public/platform/WebVector.h"
 #include "v8/include/v8.h"
 
 class ChromeRenderViewTest;
 class GURL;
 class ModuleSystem;
 class URLPattern;
 struct ExtensionMsg_ExternalConnectionInfo;
 struct ExtensionMsg_Loaded_Params;
 
 namespace WebKit {
@@ skipping 57 matching lines @@
   void DidCreateScriptContext(WebKit::WebFrame* frame,
                               v8::Handle<v8::Context> context,
                               int extension_group,
                               int world_id);
   void WillReleaseScriptContext(WebKit::WebFrame* frame,
                                 v8::Handle<v8::Context> context,
                                 int world_id);
 
   void DidCreateDocumentElement(WebKit::WebFrame* frame);
 
+  void DidMatchCSS(
+      WebKit::WebFrame* frame,
+      const WebKit::WebVector<WebKit::WebString>& newly_matching_selectors,
+      const WebKit::WebVector<WebKit::WebString>& stopped_matching_selectors);
+
   // TODO(mpcomplete): remove. http://crbug.com/100411
   bool IsAdblockWithWebRequestInstalled() const {
     return webrequest_adblock_;
   }
   bool IsAdblockPlusWithWebRequestInstalled() const {
     return webrequest_adblock_plus_;
   }
   bool IsOtherExtensionWithWebRequestInstalled() const {
     return webrequest_other_;
   }
@@ skipping 189 matching lines @@
   // The platforms system font family and size;
   std::string system_font_family_;
   std::string system_font_size_;
 
   DISALLOW_COPY_AND_ASSIGN(Dispatcher);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_RENDERER_EXTENSIONS_DISPATCHER_H_