Define kAlarmGranularity and use it in the non-test QUIC code.

gfe-relnote: n/a (Define a constant)
PiperOrigin-RevId: 286223502
Change-Id: I71046cd1bcb9f20aadcbab9748697ca1554b34a4

quic/core/quic_constants.h

diff --git a/quic/core/quic_constants.h b/quic/core/quic_constants.h
index 0b087b4..aad6d3a 100644
--- a/quic/core/quic_constants.h
+++ b/quic/core/quic_constants.h
@@ -259,6 +259,9 @@
 // rapidly increasing.
 const QuicPacketCount kMinReceivedBeforeAckDecimation = 100;
 
+// The default alarm granularity assumed by QUIC code.
+const QuicTime::Delta kAlarmGranularity = QuicTime::Delta::FromMilliseconds(1);
+
 // Packet number of first sending packet of a connection. Please note, this
 // cannot be used as first received packet because peer can choose its starting
 // packet number.