Adds QUIC_TOO_MANY_SESSIONS_ON_SERVER error code.

net/quic/core/quic_utils.cc

Index: net/quic/core/quic_utils.cc
diff --git a/net/quic/core/quic_utils.cc b/net/quic/core/quic_utils.cc
index f944dd19a5e4ebd0abd6aa1b1075a75e61b5b58e..58909597b495249f187cc7f91bb3e13c0c833dcd 100644
--- a/net/quic/core/quic_utils.cc
+++ b/net/quic/core/quic_utils.cc
@@ -304,6 +304,7 @@ const char* QuicUtils::ErrorToString(QuicErrorCode error) {
     RETURN_STRING_LITERAL(QUIC_MULTIPATH_PATH_NOT_ACTIVE);
     RETURN_STRING_LITERAL(QUIC_TOO_MANY_FRAME_GAPS);
     RETURN_STRING_LITERAL(QUIC_STREAM_SEQUENCER_INVALID_STATE);
+    RETURN_STRING_LITERAL(QUIC_TOO_MANY_SESSIONS_ON_SERVER);
     RETURN_STRING_LITERAL(QUIC_LAST_ERROR);
     // Intentionally have no default case, so we'll break the build
     // if we add errors and don't put them here.