Add an Update method on QuicAlarm which contains a granularity. Also

net/quic/quic_alarm.h

 // 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.
 
 #ifndef NET_QUIC_QUIC_ALARM_H_
 #define NET_QUIC_QUIC_ALARM_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "net/base/net_export.h"
 #include "net/quic/quic_time.h"
@@ skipping 24 matching lines @@
   // the alarm is set.  To reschedule an alarm, call Cancel() first,
   // then Set().
   void Set(QuicTime deadline);
 
   // Cancels the alarm.  May be called repeatedly.  Does not
   // guarantee that the underlying scheduling system will remove
   // the alarm's associated task, but guarantees that the
   // delegates OnAlarm method will not be called.
   void Cancel();
 
+  // Cancels and sets the alarm if the |deadline| is farther from the current
+  // deadline than |granularity|, and otherwise does nothing.  If |deadline| is
+  // not initialized, the alarm is cancelled.
+  void Update(QuicTime deadline, QuicTime::Delta granularity);
+
   bool IsSet() const;
 
   QuicTime deadline() const { return deadline_; }
 
  protected:
   // Subclasses implement this method to perform the platform-specific
   // scheduling of the alarm.  Is called from Set() or Fire(), after the
   // deadline has been updated.
   virtual void SetImpl() = 0;
 
@@ skipping 13 matching lines @@
  private:
   scoped_ptr<Delegate> delegate_;
   QuicTime deadline_;
 
   DISALLOW_COPY_AND_ASSIGN(QuicAlarm);
 };
 
 }  // namespace net
 
 #endif  // NET_QUIC_QUIC_ALARM_H_