IOThread: Use URLRequestContextBuilder::NetworkSessionParams.

net/quic/core/quic_versions.h

Index: net/quic/core/quic_versions.h
diff --git a/net/quic/core/quic_versions.h b/net/quic/core/quic_versions.h
index 1ddffe1ce554484826f709c7b54d982bdf03d1e1..8f76b2f5af5618941ef84bb8a06c74503bd8b919 100644
--- a/net/quic/core/quic_versions.h
+++ b/net/quic/core/quic_versions.h
@@ -39,6 +39,9 @@ enum QuicVersion {
                          // splits into MAX_DATA and MAX_STREAM_DATA, BLOCKED
                          // frame split into BLOCKED and STREAM_BLOCKED frames
 
+  QUIC_VERSION_DEFAULT = QUIC_VERSION_37,  // Default version enabled in
+                                           // HttpNetworkSessions.
+
   // IMPORTANT: if you are adding to this list, follow the instructions at
   // http://sites/quic/adding-and-removing-versions
 };