Update from https://crrev.com/304121

net/quic/quic_stream_factory.cc

Index: net/quic/quic_stream_factory.cc
diff --git a/net/quic/quic_stream_factory.cc b/net/quic/quic_stream_factory.cc
index cf706086d4507921c5d41435dcd96238ba02f234..076797af0a0bc5e687762d7a9b617e4ecb2b28ea 100644
--- a/net/quic/quic_stream_factory.cc
+++ b/net/quic/quic_stream_factory.cc
@@ -944,6 +944,14 @@ int QuicStreamFactory::CreateSession(
     }
   }
 
+  if (quic_server_info_factory_ && !server_info) {
+    // Start the disk cache loading so that we can persist the newer QUIC server
+    // information and/or inform the disk cache that we have reused
+    // |server_info|.
+    server_info.reset(quic_server_info_factory_->GetForServer(server_id));
+    server_info->Start();
+  }
+
   *session = new QuicClientSession(
       connection, socket.Pass(), this, transport_security_state_,
       server_info.Pass(), config, server_id.is_https(),
@@ -985,6 +993,8 @@ void QuicStreamFactory::ActivateSession(
 void QuicStreamFactory::InitializeCachedStateInCryptoConfig(
     const QuicServerId& server_id,
     const scoped_ptr<QuicServerInfo>& server_info) {
+  // |server_info| will be NULL, if a non-empty server config already exists in
+  // the memory cache. This is a minor optimization to avoid LookupOrCreate.
   if (!server_info)
     return;
 
@@ -993,6 +1003,27 @@ void QuicStreamFactory::InitializeCachedStateInCryptoConfig(
   if (!cached->IsEmpty())
     return;
 
+  if (http_server_properties_) {
+    if (quic_supported_servers_at_startup_.empty()) {
+      for (const std::pair<net::HostPortPair, net::AlternateProtocolInfo>&
+               key_value : http_server_properties_->alternate_protocol_map()) {
+        if (key_value.second.protocol == QUIC) {
+          quic_supported_servers_at_startup_.insert(key_value.first);
+        }
+      }
+    }
+
+    // TODO(rtenneti): Delete the following histogram after collecting stats.
+    // If the AlternateProtocolMap contained an entry for this host, check if
+    // the disk cache contained an entry for it.
+    if (ContainsKey(quic_supported_servers_at_startup_,
+                    server_id.host_port_pair())) {
+      UMA_HISTOGRAM_BOOLEAN(
+          "Net.QuicServerInfo.ExpectConfigMissingFromDiskCache",
+          server_info->state().server_config.empty());
+    }
+  }
+
   if (!cached->Initialize(server_info->state().server_config,
                           server_info->state().source_address_token,
                           server_info->state().certs,