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 328fb7084dc43fb5cb537d7103db128f55dfe87b..e4a51e4728b8a14924348086fbba4d7aefba7076 100644
--- a/net/base/network_quality.h
+++ b/net/base/network_quality.h
@@ -21,8 +21,12 @@ class NET_EXPORT_PRIVATE NetworkQuality {
   NetworkQuality(const base::TimeDelta& rtt,
                  int32_t downstream_throughput_kbps);
 
+  NetworkQuality(const NetworkQuality& other);
+
   ~NetworkQuality();
 
+  NetworkQuality& operator=(const NetworkQuality& other);
+
   // Returns the estimate of the round trip time.
   const base::TimeDelta& rtt() const { return rtt_; }
 
@@ -34,10 +38,10 @@ class NET_EXPORT_PRIVATE NetworkQuality {
 
  private:
   // Estimated round trip time.
-  const base::TimeDelta rtt_;
+  base::TimeDelta rtt_;
 
   // Estimated downstream throughput in Kbps.
-  const int32_t downstream_throughput_kbps_;
+  int32_t downstream_throughput_kbps_;
 };
 
 }  // namespace net