Convert TODO to a comment on why a temporary is needed on the rv or writer()

BUG=none
TEST=none

Change-Id: Idc6ca0e402c5a236dd6c1282bd562d67aaf21866
Reviewed-on: https://gerrit.chromium.org/gerrit/11586
Commit-Ready: Gaurav Shah <gauravsh@chromium.org>
Reviewed-by: Gaurav Shah <gauravsh@chromium.org>
Tested-by: Gaurav Shah <gauravsh@chromium.org>
diff --git a/wifi_service.cc b/wifi_service.cc
index 8390273..308a3e5 100644
--- a/wifi_service.cc
+++ b/wifi_service.cc
@@ -244,8 +244,8 @@
 
   params[wpa_supplicant::kPropertyKeyManagement].writer().
       append_string(key_management().c_str());
-  // TODO(quiche): figure out why we can't use operator<< without the
-  // temporary variable.
+
+  // See note in dbus_adaptor.cc on why we need to use a local.
   writer = params[wpa_supplicant::kNetworkPropertySSID].writer();
   writer << ssid_;