Introduce NetworkDelegate's implementation in extensions.

extensions/browser/api/web_request/web_request_event_router_delegate.h

 // Copyright 2014 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 EXTENSIONS_BROWSER_API_WEB_REQUEST_WEB_REQUEST_EVENT_ROUTER_DELEGATE_H_
 #define EXTENSIONS_BROWSER_API_WEB_REQUEST_WEB_REQUEST_EVENT_ROUTER_DELEGATE_H_
 
 #include <string>
 
 #include "base/values.h"
@@ skipping 16 matching lines @@
 
 // A delegate class of WebRequestApi that are not a part of chrome.
 class WebRequestEventRouterDelegate {
  public:
   WebRequestEventRouterDelegate();
   virtual ~WebRequestEventRouterDelegate();
 
   // Looks up the tab and window ID for a given request.
   // Called on the IO thread.
   virtual void ExtractExtraRequestDetails(
-      net::URLRequest* request, base::DictionaryValue* out) = 0;
+      net::URLRequest* request, base::DictionaryValue* out);
 
   // Called to check extra parameters (e.g., tab_id, windown_id) when filtering
   // event listeners.
   virtual bool OnGetMatchingListenersImplCheck(
       int tab_id, int window_id, net::URLRequest* request);
 
   // Logs an extension action.
   virtual void LogExtensionActivity(
       content::BrowserContext* browser_context,
       bool is_incognito,
       const std::string& extension_id,
       const GURL& url,
       const std::string& api_call,
-       scoped_ptr<base::DictionaryValue> details) = 0;
+       scoped_ptr<base::DictionaryValue> details) {};
 
   DISALLOW_COPY_AND_ASSIGN(WebRequestEventRouterDelegate);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_BROWSER_API_WEB_REQUEST_WEB_REQUEST_EVENT_ROUTER_DELEGATE_H_