Move JoinString to the base namespace.

extensions/browser/api/vpn_provider/vpn_provider_api.cc

Index: extensions/browser/api/vpn_provider/vpn_provider_api.cc
diff --git a/extensions/browser/api/vpn_provider/vpn_provider_api.cc b/extensions/browser/api/vpn_provider/vpn_provider_api.cc
index 069f171fb7e7272e8d76a7f4877971ec9c30f8ef..e3b80aed2e0b54054b8538e8aa2880c2ec1f7f86 100644
--- a/extensions/browser/api/vpn_provider/vpn_provider_api.cc
+++ b/extensions/browser/api/vpn_provider/vpn_provider_api.cc
@@ -112,13 +112,14 @@ void ConvertParameters(const api_vpn::Parameters& parameters,
   parameter_value->SetStringWithoutPathExpansion(
       shill::kSubnetPrefixParameterThirdPartyVpn, cidr_parts[1]);
 
+  std::string ip_delimiter(1, shill::kIPDelimiter);
   parameter_value->SetStringWithoutPathExpansion(
       shill::kExclusionListParameterThirdPartyVpn,
-      JoinString(parameters.exclusion_list, shill::kIPDelimiter));
+      base::JoinString(parameters.exclusion_list, ip_delimiter));
 
   parameter_value->SetStringWithoutPathExpansion(
       shill::kInclusionListParameterThirdPartyVpn,
-      JoinString(parameters.inclusion_list, shill::kIPDelimiter));
+      base::JoinString(parameters.inclusion_list, ip_delimiter));
 
   if (parameters.mtu) {
     parameter_value->SetStringWithoutPathExpansion(
@@ -131,15 +132,16 @@ void ConvertParameters(const api_vpn::Parameters& parameters,
         *parameters.broadcast_address);
   }
 
+  std::string non_ip_delimiter(1, shill::kNonIPDelimiter);
   if (parameters.domain_search) {
     parameter_value->SetStringWithoutPathExpansion(
         shill::kDomainSearchParameterThirdPartyVpn,
-        JoinString(*parameters.domain_search, shill::kNonIPDelimiter));
+        base::JoinString(*parameters.domain_search, non_ip_delimiter));
   }
 
   parameter_value->SetStringWithoutPathExpansion(
       shill::kDnsServersParameterThirdPartyVpn,
-      JoinString(parameters.dns_servers, shill::kIPDelimiter));
+      base::JoinString(parameters.dns_servers, ip_delimiter));
 
   return;
 }