shill: Propagate Cellular errors to the DBus caller.

BUG=chromium-os:19547
TEST=unit tests

Change-Id: Ieda54d89d977a48718302c6e1e1c7927e3cf2dba
Reviewed-on: http://gerrit.chromium.org/gerrit/6603
Reviewed-by: Darin Petkov <petkov@chromium.org>
Tested-by: Darin Petkov <petkov@chromium.org>
diff --git a/cellular_service.cc b/cellular_service.cc
index 487df55..471ad4c 100644
--- a/cellular_service.cc
+++ b/cellular_service.cc
@@ -45,8 +45,8 @@
 
 CellularService::~CellularService() { }
 
-void CellularService::Connect() {
-  cellular_->Connect();
+void CellularService::Connect(Error *error) {
+  cellular_->Connect(error);
 }
 
 void CellularService::Disconnect() { }