Fix QUIC crash when ProofSource::GetProof fails

net/quic/test_tools/failing_proof_source.h

+// Copyright (c) 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef NET_QUIC_TEST_TOOLS_FAILING_PROOF_SOURCE_H_
+#define NET_QUIC_TEST_TOOLS_FAILING_PROOF_SOURCE_H_
+
+#include "net/quic/core/crypto/proof_source.h"
+
+namespace net {
+namespace test {
+
+class FailingProofSource : public ProofSource {
+ public:
+  bool GetProof(const QuicSocketAddress& server_address,
+                const std::string& hostname,
+                const std::string& server_config,
+                QuicVersion quic_version,
+                base::StringPiece chlo_hash,
+                const QuicTagVector& connection_options,
+                QuicReferenceCountedPointer<ProofSource::Chain>* out_chain,
+                QuicCryptoProof* out_proof) override;
+
+  void GetProof(const QuicSocketAddress& server_address,
+                const std::string& hostname,
+                const std::string& server_config,
+                QuicVersion quic_version,
+                base::StringPiece chlo_hash,
+                const QuicTagVector& connection_options,
+                std::unique_ptr<Callback> callback) override;
+};
+
+}  // namespace test
+}  // namespace net
+
+#endif  // NET_QUIC_TEST_TOOLS_FAILING_PROOF_SOURCE_H_