Revert of Move JoinString to the base namespace

chrome/browser/ssl/certificate_error_report.cc

 // Copyright 2015 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.
 
 #include "chrome/browser/ssl/certificate_error_report.h"
 
 #include <vector>
 
 #include "base/stl_util.h"
 #include "base/strings/string_util.h"
@@ skipping 38 matching lines @@
   if (cert_status & net::CERT_STATUS_NO_REVOCATION_MECHANISM)
     report->add_cert_error(CertLoggerRequest::ERR_CERT_NO_REVOCATION_MECHANISM);
 }
 
 bool CertificateChainToString(scoped_refptr<net::X509Certificate> cert,
                               std::string* result) {
   std::vector<std::string> pem_encoded_chain;
   if (!cert->GetPEMEncodedChain(&pem_encoded_chain))
     return false;
 
-  *result = base::JoinString(pem_encoded_chain, base::StringPiece());
+  *result = JoinString(pem_encoded_chain, std::string());
   return true;
 }
 
 }  // namespace
 
 CertificateErrorReport::CertificateErrorReport()
     : cert_report_(new CertLoggerRequest()) {
 }
 
 CertificateErrorReport::CertificateErrorReport(const std::string& hostname,
@@ skipping 54 matching lines @@
       break;
   }
 
   interstitial_info->set_user_proceeded(proceed_decision == USER_PROCEEDED);
   interstitial_info->set_overridable(overridable == INTERSTITIAL_OVERRIDABLE);
 }
 
 const std::string& CertificateErrorReport::hostname() const {
   return cert_report_->hostname();
 }