Use overloaded operators with QuicTime for addition, subtraction and scalar

net/quic/quic_sustained_bandwidth_recorder.cc

Index: net/quic/quic_sustained_bandwidth_recorder.cc
diff --git a/net/quic/quic_sustained_bandwidth_recorder.cc b/net/quic/quic_sustained_bandwidth_recorder.cc
index 41aa51e70710c9683225be49e1b8b7d82dbed6f7..b4b4a6168c630910dd6ca3250d0233d2a7c026ec 100644
--- a/net/quic/quic_sustained_bandwidth_recorder.cc
+++ b/net/quic/quic_sustained_bandwidth_recorder.cc
@@ -41,7 +41,7 @@ void QuicSustainedBandwidthRecorder::RecordEstimate(bool in_recovery,
 
   // If we have been recording for at least 3 * srtt, then record the latest
   // bandwidth estimate as a valid sustained bandwidth estimate.
-  if (estimate_time.Subtract(start_time_) >= srtt.Multiply(3)) {
+  if (estimate_time - start_time_ >= 3 * srtt) {
     has_estimate_ = true;
     bandwidth_estimate_recorded_during_slow_start_ = in_slow_start;
     bandwidth_estimate_ = bandwidth;