Cleanup: Remove some std::map::operator[] usage in ApiResourceManager.

extensions/browser/api/sockets_udp/udp_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_udp/udp_socket_event_dispatcher.h"
 
+#include "base/lazy_instance.h"
 #include "extensions/browser/api/socket/udp_socket.h"
 #include "extensions/browser/event_router.h"
 #include "extensions/browser/extensions_browser_client.h"
 #include "net/base/net_errors.h"
 
 namespace extensions {
 namespace core_api {
 
 using content::BrowserThread;
 
@@ skipping 156 matching lines @@
       reinterpret_cast<content::BrowserContext*>(browser_context_id);
   if (!extensions::ExtensionsBrowserClient::Get()->IsValidContext(context))
     return;
   EventRouter* router = EventRouter::Get(context);
   if (router)
     router->DispatchEventToExtension(extension_id, event.Pass());
 }
 
 }  // namespace core_api
 }  // namespace extensions