Land Recent QUIC changes.

net/quic/quic_time.cc

Index: net/quic/quic_time.cc
diff --git a/net/quic/quic_time.cc b/net/quic/quic_time.cc
index fa0d51628f9e6d78b26dde88e02ee67e000b669d..a56775663e4969b36cbe01713f419576143ed549 100644
--- a/net/quic/quic_time.cc
+++ b/net/quic/quic_time.cc
@@ -104,6 +104,11 @@ QuicWallTime QuicWallTime::FromUNIXSeconds(uint64 seconds) {
   return QuicWallTime(seconds);
 }
 
+// static
+QuicWallTime QuicWallTime::Zero() {
+  return QuicWallTime(0);
+}
+
 uint64 QuicWallTime::ToUNIXSeconds() const {
   return seconds_;
 }
@@ -116,6 +121,10 @@ bool QuicWallTime::IsBefore(QuicWallTime other) const {
   return seconds_ < other.seconds_;
 }
 
+bool QuicWallTime::IsZero() const {
+  return seconds_ == 0;
+}
+
 QuicTime::Delta QuicWallTime::AbsoluteDifference(QuicWallTime other) const {
   uint64 d;