Refactoring output of ProofSource::GetProof (no functional changes).

net/quic/quartc/quartc_session.cc

Index: net/quic/quartc/quartc_session.cc
diff --git a/net/quic/quartc/quartc_session.cc b/net/quic/quartc/quartc_session.cc
index b89dc07734975013b4935b09087a2f8ee2454e85..5b960f9b66953faeea6bbb4c26db708ace0d7d0c 100644
--- a/net/quic/quartc/quartc_session.cc
+++ b/net/quic/quartc/quartc_session.cc
@@ -35,13 +35,12 @@ class DummyProofSource : public net::ProofSource {
                 base::StringPiece chlo_hash,
                 const net::QuicTagVector& connection_options,
                 scoped_refptr<net::ProofSource::Chain>* out_chain,
-                std::string* out_signature,
-                std::string* out_leaf_cert_sct) override {
+                net::QuicCryptoProof* proof) override {
     std::vector<std::string> certs;
     certs.push_back("Dummy cert");
     *out_chain = new ProofSource::Chain(certs);
-    *out_signature = "Dummy signature";
-    *out_leaf_cert_sct = "Dummy timestamp";
+    proof->signature = "Dummy signature";
+    proof->leaf_cert_scts = "Dummy timestamp";
     return true;
   }