Remove using namespace in net/quic/quic_stream_sequencer.h

net/tools/quic/quic_dispatcher_test.cc

Index: net/tools/quic/quic_dispatcher_test.cc
diff --git a/net/tools/quic/quic_dispatcher_test.cc b/net/tools/quic/quic_dispatcher_test.cc
index 45cddb011fc75756792eb5a468cad264f1166d65..fc1e10d59e7c9a02df9ac02d094bff0e9d74ce82 100644
--- a/net/tools/quic/quic_dispatcher_test.cc
+++ b/net/tools/quic/quic_dispatcher_test.cc
@@ -29,6 +29,7 @@ using net::test::MockSession;
 using net::test::ValueRestore;
 using net::tools::test::MockConnection;
 using std::make_pair;
+using std::string;
 using testing::DoAll;
 using testing::InSequence;
 using testing::Invoke;