Add QuicStringPiece which is actually StringPiece.

net/quic/test_tools/failing_proof_source.h

Index: net/quic/test_tools/failing_proof_source.h
diff --git a/net/quic/test_tools/failing_proof_source.h b/net/quic/test_tools/failing_proof_source.h
index dfc72fe32fe967fb20cadf67553c24dc4cbe47b5..a73a596e906a56330afc8ab195bef14c3a506c5e 100644
--- a/net/quic/test_tools/failing_proof_source.h
+++ b/net/quic/test_tools/failing_proof_source.h
@@ -6,6 +6,7 @@
 #define NET_QUIC_TEST_TOOLS_FAILING_PROOF_SOURCE_H_
 
 #include "net/quic/core/crypto/proof_source.h"
+#include "net/quic/platform/api/quic_string_piece.h"
 
 namespace net {
 namespace test {
@@ -16,7 +17,7 @@ class FailingProofSource : public ProofSource {
                 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) override;
 };