Only set one QUIC sending alarm at once. Flag protected by --quic_only_one_sending_alarm.

net/quic/quic_connection.h

 // Copyright (c) 2012 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.
 //
 // The entity that handles framing writes for a Quic client or server.
 // Each QuicSession will have a connection associated with it.
 //
 // On the server side, the Dispatcher handles the raw reads, and hands off
 // packets via ProcessUdpPacket for framing and processing.
 //
@@ skipping 948 matching lines @@
 
   // An alarm that fires when an ACK should be sent to the peer.
   QuicArenaScopedPtr<QuicAlarm> ack_alarm_;
   // An alarm that fires when a packet needs to be retransmitted.
   QuicArenaScopedPtr<QuicAlarm> retransmission_alarm_;
   // An alarm that is scheduled when the SentPacketManager requires a delay
   // before sending packets and fires when the packet may be sent.
   QuicArenaScopedPtr<QuicAlarm> send_alarm_;
   // An alarm that is scheduled when the connection can still write and there
   // may be more data to send.
+  // TODO(ianswett): Remove resume_writes_alarm when deprecating
+  // FLAGS_quic_only_one_sending_alarm
   QuicArenaScopedPtr<QuicAlarm> resume_writes_alarm_;
   // An alarm that fires when the connection may have timed out.
   QuicArenaScopedPtr<QuicAlarm> timeout_alarm_;
   // An alarm that fires when a ping should be sent.
   QuicArenaScopedPtr<QuicAlarm> ping_alarm_;
   // An alarm that fires when an MTU probe should be sent.
   QuicArenaScopedPtr<QuicAlarm> mtu_discovery_alarm_;
 
   // Neither visitor is owned by this class.
   QuicConnectionVisitorInterface* visitor_;
@@ skipping 78 matching lines @@
 
   // If true, multipath is enabled for this connection.
   bool multipath_enabled_;
 
   DISALLOW_COPY_AND_ASSIGN(QuicConnection);
 };
 
 }  // namespace net
 
 #endif  // NET_QUIC_QUIC_CONNECTION_H_