Remove redundant mapping of net errors to strings.

net/quic/crypto/proof_verifier_chromium.cc

Index: net/quic/crypto/proof_verifier_chromium.cc
diff --git a/net/quic/crypto/proof_verifier_chromium.cc b/net/quic/crypto/proof_verifier_chromium.cc
index 443c0e352ea5336987ff7142e1609d4dd99c108b..13399fdaa923d72740b54da621cdd637768c4f6b 100644
--- a/net/quic/crypto/proof_verifier_chromium.cc
+++ b/net/quic/crypto/proof_verifier_chromium.cc
@@ -229,8 +229,9 @@ int ProofVerifierChromium::Job::DoVerifyCertComplete(int result) {
   verifier_.reset();
 
   if (result != OK) {
+    std::string error_string = ErrorToString(result);
     error_details_ = StringPrintf("Failed to verify certificate chain: %s",
-                                  ErrorToString(result));
+                                  error_string.c_str());
     DLOG(WARNING) << error_details_;
   }
 
@@ -240,8 +241,8 @@ int ProofVerifierChromium::Job::DoVerifyCertComplete(int result) {
 }
 
 bool ProofVerifierChromium::Job::VerifySignature(const string& signed_data,
-                                            const string& signature,
-                                            const string& cert) {
+                                                 const string& signature,
+                                                 const string& cert) {
   StringPiece spki;
   if (!asn1::ExtractSPKIFromDERCert(cert, &spki)) {
     DLOG(WARNING) << "ExtractSPKIFromDERCert failed";