Fix QUIC crash when ProofSource::GetProof fails

net/quic/test_tools/quic_crypto_server_config_peer.cc

Index: net/quic/test_tools/quic_crypto_server_config_peer.cc
diff --git a/net/quic/test_tools/quic_crypto_server_config_peer.cc b/net/quic/test_tools/quic_crypto_server_config_peer.cc
index 3856b9f8e701d874a9c25cc9b739106a5dea0ed4..d9a47f7747b8d8fc5711e644ddf242eaa16044dd 100644
--- a/net/quic/test_tools/quic_crypto_server_config_peer.cc
+++ b/net/quic/test_tools/quic_crypto_server_config_peer.cc
@@ -42,6 +42,11 @@ ProofSource* QuicCryptoServerConfigPeer::GetProofSource() const {
   return server_config_->proof_source_.get();
 }
 
+void QuicCryptoServerConfigPeer::ResetProofSource(
+    std::unique_ptr<ProofSource> proof_source) {
+  server_config_->proof_source_ = std::move(proof_source);
+}
+
 string QuicCryptoServerConfigPeer::NewSourceAddressToken(
     string config_id,
     SourceAddressTokens previous_tokens,