shill: enable (don't disable) -Wunused

having fixed an unused parameter in the dbus-c++ headers, those
headers no longer have unused parameters. so, if we fix up unused
parameters in shill code, we can compile with -Wunused. (this is
implied by -Wall, as long as we don't override with -Wno-unused.)

BUG=chromium-os:20779
TEST=unittests

- comment out unused parameters in function definitions
- remove some unused local variables
- also: fix an old-style cast

Change-Id: Ie654a7b34d622cecb0f26bd47c17813fe8423001
Reviewed-on: http://gerrit.chromium.org/gerrit/8365
Tested-by: mukesh agrawal <quiche@chromium.org>
Reviewed-by: Paul Stewart <pstew@chromium.org>
diff --git a/service_dbus_adaptor.cc b/service_dbus_adaptor.cc
index e64e2f5..f151f01 100644
--- a/service_dbus_adaptor.cc
+++ b/service_dbus_adaptor.cc
@@ -64,7 +64,8 @@
   DBusAdaptor::DispatchOnType(service_->mutable_store(), name, value, &error);
 }
 
-void ServiceDBusAdaptor::ClearProperty(const string& , ::DBus::Error &error) {
+void ServiceDBusAdaptor::ClearProperty(const string& ,
+                                       ::DBus::Error &/*error*/) {
 }
 
 void ServiceDBusAdaptor::Connect(::DBus::Error &error) {
@@ -73,18 +74,18 @@
   e.ToDBusError(&error);
 }
 
-void ServiceDBusAdaptor::Disconnect(::DBus::Error &error) {
+void ServiceDBusAdaptor::Disconnect(::DBus::Error &/*error*/) {
 }
 
-void ServiceDBusAdaptor::Remove(::DBus::Error &error) {
+void ServiceDBusAdaptor::Remove(::DBus::Error &/*error*/) {
 }
 
 void ServiceDBusAdaptor::MoveBefore(const ::DBus::Path& ,
-                                    ::DBus::Error &error) {
+                                    ::DBus::Error &/*error*/) {
 }
 
 void ServiceDBusAdaptor::MoveAfter(const ::DBus::Path& ,
-                                   ::DBus::Error &error) {
+                                   ::DBus::Error &/*error*/) {
 }
 
 void ServiceDBusAdaptor::ActivateCellularModem(const string &carrier,