Add in-memory caching of network quality estimates across network changes.

net/base/network_quality.h

Index: net/base/network_quality.h
diff --git a/net/base/network_quality.h b/net/base/network_quality.h
index 4e2985776e0f4a8430b80c7523751391b4b0c0b7..054aea1b41296db0c1a0c927a87d3cf2eb59da10 100644
--- a/net/base/network_quality.h
+++ b/net/base/network_quality.h
@@ -23,10 +23,17 @@ struct NET_EXPORT_PRIVATE NetworkQuality {
         peak_throughput_kbps(peak_throughput_kbps),
         peak_throughput_kbps_confidence(peak_throughput_kbps_confidence) {}
 
+  NetworkQuality(const NetworkQuality& other)
+      : fastest_rtt(other.fastest_rtt),
+        fastest_rtt_confidence(other.fastest_rtt_confidence),
+        peak_throughput_kbps(other.peak_throughput_kbps),
+        peak_throughput_kbps_confidence(other.peak_throughput_kbps_confidence) {
+  }
+
   ~NetworkQuality() {}
 
   // The fastest round trip time observed for the current connection.
-  const base::TimeDelta fastest_rtt;
+  base::TimeDelta fastest_rtt;
 
   // Confidence of the |fastest_rtt| estimate. Value lies between 0.0 and 1.0
   // with 0.0 being no confidence and 1.0 implying that estimates are same as
@@ -36,7 +43,7 @@ struct NET_EXPORT_PRIVATE NetworkQuality {
   const double fastest_rtt_confidence;
 
   // Peak throughput in Kbps observed for the current connection.
-  const uint64_t peak_throughput_kbps;
+  uint64_t peak_throughput_kbps;
 
   // Confidence of the |peak_throughput_kbps| estimate. Value lies between 0.0
   // and 1.0 with 0.0 being no confidence and 1.0 implying that estimates are
@@ -44,6 +51,9 @@ struct NET_EXPORT_PRIVATE NetworkQuality {
   // TODO(tbansal): Define units so values intermediate between 0.0 and 1.0 are
   // meaningful.
   const double peak_throughput_kbps_confidence;
+
+ private:
+  DISALLOW_ASSIGN(NetworkQuality);
 };
 
 }  // namespace net