Change uses of base::JoinString to pass StringPieces where possible.

chromeos/network/onc/onc_validator.cc

 // Copyright (c) 2012 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 "chromeos/network/onc/onc_validator.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
 
 #include "base/json/json_writer.h"
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
 #include "base/strings/string_number_conversions.h"
+#include "base/strings/string_piece.h"
 #include "base/strings/string_util.h"
 #include "base/values.h"
 #include "chromeos/network/onc/onc_signature.h"
 
 namespace chromeos {
 namespace onc {
 
 namespace {
 
 // According to the IEEE 802.11 standard the SSID is a series of 0 to 32 octets.
@@ skipping 282 matching lines @@
   else if (cert_type == kRef)
     all_required_exist &= RequireField(*result, kClientCertRef);
 
   return !error_on_missing_field_ || all_required_exist;
 }
 
 namespace {
 
 std::string JoinStringRange(const std::vector<const char*>& strings,
                             const std::string& separator) {
-  std::vector<std::string> string_vector;
-  std::copy(strings.begin(), strings.end(), std::back_inserter(string_vector));
+  std::vector<base::StringPiece> string_vector(strings.begin(), strings.end());
   return base::JoinString(string_vector, separator);
 }
 
 }  // namespace
 
 bool Validator::IsValidValue(const std::string& field_value,
                              const std::vector<const char*>& valid_values) {
   for (const char* it : valid_values) {
     if (field_value == it)
       return true;
@@ skipping 686 matching lines @@
 }
 
 std::string Validator::MessageHeader() {
   std::string path = path_.empty() ? "toplevel" : base::JoinString(path_, ".");
   std::string message = "At " + path + ": ";
   return message;
 }
 
 }  // namespace onc
 }  // namespace chromeos