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

net/quic/quic_alarm.h

Index: net/quic/quic_alarm.h
diff --git a/net/quic/quic_alarm.h b/net/quic/quic_alarm.h
index bee51577395c2c586c288fb7d12ba9731eb38b8c..5df4fe051603dbff1981c87562bddc6c53eef4a7 100644
--- a/net/quic/quic_alarm.h
+++ b/net/quic/quic_alarm.h
@@ -42,6 +42,11 @@ class NET_EXPORT_PRIVATE QuicAlarm {
   // 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_; }