Add QuicStringPiece which is actually StringPiece.

net/quic/test_tools/failing_proof_source.cc

Index: net/quic/test_tools/failing_proof_source.cc
diff --git a/net/quic/test_tools/failing_proof_source.cc b/net/quic/test_tools/failing_proof_source.cc
index a45bf5264dea1ffca7bf074c067ad76b1092ae23..45ce8e85a5f44658bfc6d329421932853ca0a070 100644
--- a/net/quic/test_tools/failing_proof_source.cc
+++ b/net/quic/test_tools/failing_proof_source.cc
@@ -11,7 +11,7 @@ void FailingProofSource::GetProof(const QuicSocketAddress& server_address,
                                   const std::string& hostname,
                                   const std::string& server_config,
                                   QuicVersion quic_version,
-                                  base::StringPiece chlo_hash,
+                                  QuicStringPiece chlo_hash,
                                   const QuicTagVector& connection_options,
                                   std::unique_ptr<Callback> callback) {
   callback->Run(false, nullptr, QuicCryptoProof(), nullptr);