Allow using system libevent instead of the bundled one.

net/base/telnet_server.cc

 // Copyright (c) 2006-2008 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 "build/build_config.h"
 
 #if defined(OS_WIN)
 // winsock2.h must be included first in order to ensure it is included before
 // windows.h.
 #include <winsock2.h>
 #elif defined(OS_POSIX)
 #include <errno.h>
 #include <sys/socket.h>
 #include "base/message_loop.h"
 #include "net/base/net_errors.h"
+#if defined(USE_SYSTEM_LIBEVENT)
+#include <event.h>
+#else
 #include "third_party/libevent/event.h"
+#endif
 #include "base/message_pump_libevent.h"
 #endif
 
 #include "base/eintr_wrapper.h"
 #include "net/base/telnet_server.h"
 
 #if defined(OS_POSIX)
 // Used same name as in Windows to avoid #ifdef where refrenced
 #define SOCKET int
 const int INVALID_SOCKET = -1;
@@ skipping 241 matching lines @@
     } else {
       const char *data = buf;
       for (int i = 0; i < len; ++i) {
         unsigned char c = static_cast<unsigned char>(*data);
         StateMachineStep(c);
         data++;
       }
     }
   } while (len == kReadBufSize);
 }