Add CHECK() in UdpSocketLibevent to debug crbug.com/452121

net/udp/datagram_socket.h

 // 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.
 
 #ifndef NET_UDP_DATAGRAM_SOCKET_H_
 #define NET_UDP_DATAGRAM_SOCKET_H_
 
 #include "net/base/net_export.h"
 
 namespace net {
 
 class BoundNetLog;
 class IPEndPoint;
 
 // A datagram socket is an interface to a protocol which exchanges
 // datagrams, like UDP.
 class NET_EXPORT_PRIVATE DatagramSocket {
  public:
   // Type of source port binding to use.
   enum BindType {
     RANDOM_BIND,
     DEFAULT_BIND,
   };
 
   virtual ~DatagramSocket() {}
 
   // Close the socket.
-  virtual void Close() = 0;
+  virtual int Close() = 0;
 
   // Copy the remote udp address into |address| and return a network error code.
   virtual int GetPeerAddress(IPEndPoint* address) const = 0;
 
   // Copy the local udp address into |address| and return a network error code.
   // (similar to getsockname)
   virtual int GetLocalAddress(IPEndPoint* address) const = 0;
 
   // Gets the NetLog for this socket.
   virtual const BoundNetLog& NetLog() const = 0;
 };
 
 }  // namespace net
 
 #endif  // NET_UDP_DATAGRAM_SOCKET_H_