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/wifi.h b/wifi.h
index 8128965..04b1d09 100644
--- a/wifi.h
+++ b/wifi.h
@@ -31,9 +31,10 @@
        const std::string &address,
        int interface_index);
   virtual ~WiFi();
+
   virtual void Start();
   virtual void Stop();
-  virtual void Scan();
+  virtual void Scan(Error *error);
   virtual bool TechnologyIs(const Technology type) const;
   virtual void LinkEvent(unsigned int flags, unsigned int change);