Makes a handful of DataSources not replace the existing

chrome/browser/dom_ui/web_ui_favicon_source.h

 // Copyright (c) 2011 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_BROWSER_DOM_UI_WEB_UI_FAVICON_SOURCE_H_
 #define CHROME_BROWSER_DOM_UI_WEB_UI_FAVICON_SOURCE_H_
 #pragma once
 
 #include <string>
 
@@ skipping 12 matching lines @@
   explicit WebUIFavIconSource(Profile* profile);
 
   // Called when the network layer has requested a resource underneath
   // the path we registered.
   virtual void StartDataRequest(const std::string& path,
                                 bool is_off_the_record,
                                 int request_id);
 
   virtual std::string GetMimeType(const std::string&) const;
 
+  virtual bool ShouldReplaceExistingSource() const;
+
+ private:
   // Called when favicon data is available from the history backend.
   void OnFavIconDataAvailable(FaviconService::Handle request_handle,
                               bool know_favicon,
                               scoped_refptr<RefCountedMemory> data,
                               bool expired,
                               GURL url);
 
- private:
   // Sends the default favicon.
   void SendDefaultResponse(int request_id);
 
   virtual ~WebUIFavIconSource();
 
   Profile* profile_;
   CancelableRequestConsumerT<int, 0> cancelable_consumer_;
 
   // Raw PNG representation of the favicon to show when the favicon
   // database doesn't have a favicon for a webpage.
   scoped_refptr<RefCountedMemory> default_favicon_;
 
   DISALLOW_COPY_AND_ASSIGN(WebUIFavIconSource);
 };
 
 #endif  // CHROME_BROWSER_DOM_UI_WEB_UI_FAVICON_SOURCE_H_