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

remoting/protocol/chromium_socket_factory.cc

Index: remoting/protocol/chromium_socket_factory.cc
diff --git a/remoting/protocol/chromium_socket_factory.cc b/remoting/protocol/chromium_socket_factory.cc
index 6b2c4fc69d8038b89f975251c5ab2d84ffe7f24a..0b6504520116420a500d7f150045b3b57811770f 100644
--- a/remoting/protocol/chromium_socket_factory.cc
+++ b/remoting/protocol/chromium_socket_factory.cc
@@ -198,6 +198,12 @@ int UdpPacketSocket::SendTo(const void* data, size_t data_size,
 
 int UdpPacketSocket::Close() {
   state_ = STATE_CLOSED;
+
+  // This CHECK() was added to debug crbug.com/452121 .
+  //
+  // TODO(sergeyu): Remove once the bug is resolved.
+  CHECK_NE(socket_->Close(), net::ERR_INVALID_HANDLE);
+
   socket_.reset();
   return 0;
 }