Clear the QUIC ping alarm when a connection in closed.

net/quic/quic_connection.cc

Index: net/quic/quic_connection.cc
diff --git a/net/quic/quic_connection.cc b/net/quic/quic_connection.cc
index e8a71e85cece8a429c20317a95e65655ace30c5b..b6cfd2b81199b788f7c2196ea463d507c6196210 100644
--- a/net/quic/quic_connection.cc
+++ b/net/quic/quic_connection.cc
@@ -1792,6 +1792,7 @@ void QuicConnection::CloseConnection(QuicErrorCode error, bool from_peer) {
   // Cancel the alarms so they don't trigger any action now that the
   // connection is closed.
   ack_alarm_->Cancel();
+  ping_alarm_->Cancel();
   resume_writes_alarm_->Cancel();
   retransmission_alarm_->Cancel();
   send_alarm_->Cancel();