shill: Support for GSM network scanning.

This is mostly placeholder code since synchronous calls will cause crashes due
to timeouts.

BUG=chromium-os:19805
TEST=unit tests

Change-Id: I7ad07d6274b19b39d7955ee256c6928c9f1ce5a1
Reviewed-on: http://gerrit.chromium.org/gerrit/7895
Commit-Ready: Darin Petkov <petkov@chromium.org>
Reviewed-by: Darin Petkov <petkov@chromium.org>
Tested-by: Darin Petkov <petkov@chromium.org>
diff --git a/device.h b/device.h
index 22dd9a1..0ab72a9 100644
--- a/device.h
+++ b/device.h
@@ -63,11 +63,11 @@
   virtual bool TechnologyIs(const Technology type) const;
 
   virtual void LinkEvent(unsigned flags, unsigned change);
-  virtual void Scan();
 
   virtual void ConfigIP() {}
 
   // The default implementation sets |error| to kNotSupported.
+  virtual void Scan(Error *error);
   virtual void RegisterOnNetwork(const std::string &network_id, Error *error);
   virtual void RequirePIN(const std::string &pin, bool require, Error *error);
   virtual void EnterPIN(const std::string &pin, Error *error);