shill: Transition Cellular's state to Registered when the modem is registered.

Also, process GSM network technology types and roaming states and update the
Cellular service appropriately.

BUG=chromium-os:19676
TEST=unit tests, tested on device

Change-Id: I6606a01a07cf635cb344aef95c3145eaf2290fba
Reviewed-on: http://gerrit.chromium.org/gerrit/6768
Reviewed-by: Darin Petkov <petkov@chromium.org>
Tested-by: Darin Petkov <petkov@chromium.org>
diff --git a/modem_gsm_network_proxy.h b/modem_gsm_network_proxy.h
index 816ec7c..2a8df41 100644
--- a/modem_gsm_network_proxy.h
+++ b/modem_gsm_network_proxy.h
@@ -22,6 +22,8 @@
 
   // Inherited from ModemGSMNetworkProxyInterface.
   virtual void Register(const std::string &network_id);
+  virtual RegistrationInfo GetRegistrationInfo();
+  virtual uint32 AccessTechnology();
 
  private:
   class Proxy