Remove some unnecessary using directives from tests.

net/quic/core/quic_server_session_base_test.cc

Index: net/quic/core/quic_server_session_base_test.cc
diff --git a/net/quic/core/quic_server_session_base_test.cc b/net/quic/core/quic_server_session_base_test.cc
index 5bcc10941c6d49e3cc1196e15a39c7902d46e450..3b92d1e43dd97788901666ae8b80c4bdb31f7b4e 100644
--- a/net/quic/core/quic_server_session_base_test.cc
+++ b/net/quic/core/quic_server_session_base_test.cc
@@ -35,22 +35,6 @@
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
-using net::test::CryptoTestUtils;
-using net::test::MockQuicConnection;
-using net::test::MockQuicConnectionHelper;
-using net::test::QuicConfigPeer;
-using net::test::QuicConnectionPeer;
-using net::test::QuicSpdyStreamPeer;
-using net::test::QuicSentPacketManagerPeer;
-using net::test::QuicSessionPeer;
-using net::test::QuicSpdySessionPeer;
-using net::test::QuicSustainedBandwidthRecorderPeer;
-using net::test::SupportedVersions;
-using net::test::kClientDataStreamId1;
-using net::test::kClientDataStreamId2;
-using net::test::kClientDataStreamId3;
-using net::test::kInitialSessionFlowControlWindowForTest;
-using net::test::kInitialStreamFlowControlWindowForTest;
 using std::string;
 using testing::StrictMock;
 using testing::_;