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

net/udp/udp_socket_win.cc

Index: net/udp/udp_socket_win.cc
diff --git a/net/udp/udp_socket_win.cc b/net/udp/udp_socket_win.cc
index 928de4ac6b6eddf2f854bd6897766a171926a3f4..465c203a9b4f527647ffd4239d7e3690a22ed25a 100644
--- a/net/udp/udp_socket_win.cc
+++ b/net/udp/udp_socket_win.cc
@@ -296,11 +296,11 @@ int UDPSocketWin::Open(AddressFamily address_family) {
   return OK;
 }
 
-void UDPSocketWin::Close() {
+int UDPSocketWin::Close() {
   DCHECK(CalledOnValidThread());
 
   if (socket_ == INVALID_SOCKET)
-    return;
+    return OK;
 
   if (qos_handle_) {
     QwaveAPI::Get().CloseHandle(qos_handle_);
@@ -312,7 +312,7 @@ void UDPSocketWin::Close() {
   write_callback_.Reset();
 
   base::TimeTicks start_time = base::TimeTicks::Now();
-  closesocket(socket_);
+  int result = MapSystemError(closesocket(socket_));
   UMA_HISTOGRAM_TIMES("Net.UDPSocketWinClose",
                       base::TimeTicks::Now() - start_time);
   socket_ = INVALID_SOCKET;
@@ -326,6 +326,8 @@ void UDPSocketWin::Close() {
     core_->Detach();
     core_ = NULL;
   }
+
+  return result;
 }
 
 int UDPSocketWin::GetPeerAddress(IPEndPoint* address) const {