net doesn't depend on libevent directly now.

net/socket/tcp_server_socket_libevent.cc

 // 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.
 
 #include "net/socket/tcp_server_socket_libevent.h"
 
 #include <errno.h>
 #include <fcntl.h>
 #include <netdb.h>
 #include <sys/socket.h>
 
 #include "build/build_config.h"
 
 #if defined(OS_POSIX)
 #include <netinet/in.h>
 #endif
-#if defined(USE_SYSTEM_LIBEVENT)
-#include <event.h>
-#else
-#include "third_party/libevent/event.h"
-#endif
 
 #include "base/eintr_wrapper.h"
 #include "net/base/ip_endpoint.h"
 #include "net/base/net_errors.h"
 #include "net/base/net_util.h"
 #include "net/socket/tcp_client_socket.h"
 
 namespace net {
 
 namespace {
@@ skipping 161 matching lines @@
     accept_socket_ = NULL;
     c->Run(result);
   }
 }
 
 void TCPServerSocketLibevent::OnFileCanWriteWithoutBlocking(int fd) {
   NOTREACHED();
 }
 
 }  // namespace net