cleanup: Use EventRouter instead of ExtensionSystem::Get->event_router()

extensions/browser/api/sockets_tcp_server/tcp_server_socket_event_dispatcher.cc

 // 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.
 
 #include "extensions/browser/api/sockets_tcp_server/tcp_server_socket_event_dispatcher.h"
 
 #include "extensions/browser/api/socket/tcp_socket.h"
 #include "extensions/browser/event_router.h"
-#include "extensions/browser/extension_system.h"
 #include "extensions/browser/extensions_browser_client.h"
 #include "net/base/net_errors.h"
 
 namespace extensions {
 namespace core_api {
 
 using content::BrowserThread;
 
 static base::LazyInstance<
     BrowserContextKeyedAPIFactory<TCPServerSocketEventDispatcher> > g_factory =
@@ skipping 163 matching lines @@
 void TCPServerSocketEventDispatcher::DispatchEvent(
     void* browser_context_id,
     const std::string& extension_id,
     scoped_ptr<Event> event) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 
   content::BrowserContext* context =
       reinterpret_cast<content::BrowserContext*>(browser_context_id);
   if (!extensions::ExtensionsBrowserClient::Get()->IsValidContext(context))
     return;
-  EventRouter* router = ExtensionSystem::Get(context)->event_router();
+  EventRouter* router = EventRouter::Get(context);
   if (router)
     router->DispatchEventToExtension(extension_id, event.Pass());
 }
 
 }  // namespace core_api
 }  // namespace extensions