Only cancel QUIC alarms if they have been set. Protected behind FLAG_quic_only_cancel_set_alarms

net/quic/quic_alarm.cc

 // Copyright 2013 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.
 
 #include "net/quic/quic_alarm.h"
 
 #include "base/logging.h"
+#include "net/quic/quic_flags.h"
 
 namespace net {
 
 QuicAlarm::QuicAlarm(QuicArenaScopedPtr<Delegate> delegate)
     : delegate_(std::move(delegate)), deadline_(QuicTime::Zero()) {}
 
 QuicAlarm::~QuicAlarm() {}
 
 void QuicAlarm::Set(QuicTime deadline) {
   DCHECK(!IsSet());
   DCHECK(deadline.IsInitialized());
   deadline_ = deadline;
   SetImpl();
 }
 
 void QuicAlarm::Cancel() {
+  if (FLAGS_quic_only_cancel_set_alarms && !IsSet()) {
+    // Don't try to cancel an alarm that hasn't been set.
+    return;
+  }
   deadline_ = QuicTime::Zero();
   CancelImpl();
 }
 
 void QuicAlarm::Update(QuicTime deadline, QuicTime::Delta granularity) {
   if (!deadline.IsInitialized()) {
     Cancel();
     return;
   }
   if (std::abs(deadline.Subtract(deadline_).ToMicroseconds()) <
@@ skipping 18 matching lines @@
   // delegate_->OnAlarm() might call Set(), in which case deadline_
   // will already contain the new value, so don't overwrite it.  Also,
   // OnAlarm() might delete |this| so check |deadline| before
   // |deadline_|.
   if (deadline.IsInitialized() && !deadline_.IsInitialized()) {
     Set(deadline);
   }
 }
 
 }  // namespace net