Fixes two div by zero bugs in QUIC's BBR pacing code that caused server

net/quic/congestion_control/rtt_stats.h

Index: net/quic/congestion_control/rtt_stats.h
diff --git a/net/quic/congestion_control/rtt_stats.h b/net/quic/congestion_control/rtt_stats.h
index 5e0168704a102533701a29c72906cd937c6e6adc..b7ec6b94dcfbb05a171aade4857210c852be9a04 100644
--- a/net/quic/congestion_control/rtt_stats.h
+++ b/net/quic/congestion_control/rtt_stats.h
@@ -43,6 +43,11 @@ class NET_EXPORT_PRIVATE RttStats {
 
   QuicTime::Delta SmoothedRtt() const;
 
+  // Returns the min_rtt for the entire connection if a min has been measured.
+  // This returns an initial non-zero RTT estimate if no measurements have yet
+  // been made.
+  QuicTime::Delta MinRtt() const;
+
   int64 initial_rtt_us() const {
     return initial_rtt_us_;
   }
@@ -56,11 +61,6 @@ class NET_EXPORT_PRIVATE RttStats {
     return latest_rtt_;
   }
 
-  // Returns the min_rtt for the entire connection.
-  QuicTime::Delta min_rtt() const {
-    return min_rtt_;
-  }
-
   // Returns the min_rtt since SampleNewRecentMinRtt has been called, or the
   // min_rtt for the entire connection if SampleNewMinRtt was never called.
   QuicTime::Delta recent_min_rtt() const {