Clear cached QUIC network stats when a QUIC handshake fails.

net/http/http_server_properties_manager.h

Index: net/http/http_server_properties_manager.h
diff --git a/net/http/http_server_properties_manager.h b/net/http/http_server_properties_manager.h
index d2e6fc30849cfd3163df6ba1de1273ecafa06363..e2301c410776e0d2cb765224a85fe03a38ebac5f 100644
--- a/net/http/http_server_properties_manager.h
+++ b/net/http/http_server_properties_manager.h
@@ -150,6 +150,7 @@ class NET_EXPORT HttpServerPropertiesManager : public HttpServerProperties {
   void SetSupportsQuic(bool used_quic, const IPAddress& last_address) override;
   void SetServerNetworkStats(const url::SchemeHostPort& server,
                              ServerNetworkStats stats) override;
+  void ClearServerNetworkStats(const url::SchemeHostPort& server) override;
   const ServerNetworkStats* GetServerNetworkStats(
       const url::SchemeHostPort& server) override;
   const ServerNetworkStatsMap& server_network_stats_map() const override;
@@ -164,6 +165,8 @@ class NET_EXPORT HttpServerPropertiesManager : public HttpServerProperties {
 
  protected:
   // The location where ScheduleUpdatePrefsOnNetworkThread was called.
+  // Must be kept up to date with HttpServerPropertiesUpdatePrefsLocation in
+  // histograms.xml.
   enum Location {
     SUPPORTS_SPDY = 0,
     HTTP_11_REQUIRED = 1,
@@ -179,7 +182,8 @@ class NET_EXPORT HttpServerPropertiesManager : public HttpServerProperties {
     SET_SERVER_NETWORK_STATS = 11,
     DETECTED_CORRUPTED_PREFS = 12,
     SET_QUIC_SERVER_INFO = 13,
-    NUM_LOCATIONS = 14,
+    CLEAR_SERVER_NETWORK_STATS = 14,
+    NUM_LOCATIONS = 15,
   };
 
   // --------------------