Migrates QUIC sessions to a new network when old network is (about to be) disconnected.

net/dns/address_sorter_posix_unittest.cc

Index: net/dns/address_sorter_posix_unittest.cc
diff --git a/net/dns/address_sorter_posix_unittest.cc b/net/dns/address_sorter_posix_unittest.cc
index 9d7916dd1538fdf197ffc853809f8fd8813b5cbd..909ad3c73b7bfaa5b98eab57cca9d6721743fb59 100644
--- a/net/dns/address_sorter_posix_unittest.cc
+++ b/net/dns/address_sorter_posix_unittest.cc
@@ -65,7 +65,7 @@ class TestUDPClientSocket : public DatagramClientSocket {
     NOTIMPLEMENTED();
     return ERR_NOT_IMPLEMENTED;
   }
-  NetworkChangeNotifier::NetworkHandle GetBoundNetwork() override {
+  NetworkChangeNotifier::NetworkHandle GetBoundNetwork() const override {
     return NetworkChangeNotifier::kInvalidNetworkHandle;
   }