chromeos: Use stl utilities from the base namespace

chromeos/network/client_cert_resolver.cc

Index: chromeos/network/client_cert_resolver.cc
diff --git a/chromeos/network/client_cert_resolver.cc b/chromeos/network/client_cert_resolver.cc
index 12beecd174e555e3ba0e55f8b316de925236e9c4..d457b5308ad872682c9ecdd43837fb09640ce22f 100644
--- a/chromeos/network/client_cert_resolver.cc
+++ b/chromeos/network/client_cert_resolver.cc
@@ -387,7 +387,7 @@ void ClientCertResolver::NetworkListChanged() {
   for (NetworkStateHandler::NetworkStateList::const_iterator it =
            networks.begin(); it != networks.end(); ++it) {
     const std::string& service_path = (*it)->path();
-    if (ContainsKey(old_resolved_networks, service_path)) {
+    if (base::ContainsKey(old_resolved_networks, service_path)) {
       resolved_networks_.insert(service_path);
       continue;
     }