Remove unused return value from QuicAlarm::Delegate::OnAlarm. No behavior change, not protected.

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 9bd7279e7b760bcaa83ed0dc562d2544ad3eefed..53a823fd4250fd43d28f2a775310ca43dfabd5be 100644
--- a/net/quic/quic_alarm.h
+++ b/net/quic/quic_alarm.h
@@ -24,10 +24,8 @@ class NET_EXPORT_PRIVATE QuicAlarm {
    public:
     virtual ~Delegate() {}
 
-    // Invoked when the alarm fires.  If the return value is not
-    // infinite, then the alarm will be rescheduled at the
-    // specified time.
-    virtual QuicTime OnAlarm() = 0;
+    // Invoked when the alarm fires.
+    virtual void OnAlarm() = 0;
   };
 
   explicit QuicAlarm(QuicArenaScopedPtr<Delegate> delegate);