[shill] Start replacing bare pointers with scoped_refptrs where appropriate

BUG=chromium-os:16259
TEST=unit tests

Change-Id: I5e1531b726bbb40917d25dc3ae44da9a6a420e00
Reviewed-on: http://gerrit.chromium.org/gerrit/2236
Tested-by: Chris Masone <cmasone@chromium.org>
Reviewed-by: Darin Petkov <petkov@chromium.org>
diff --git a/ethernet.h b/ethernet.h
index 60ea5db..09e0ee5 100644
--- a/ethernet.h
+++ b/ethernet.h
@@ -29,7 +29,7 @@
 
  private:
   bool service_registered_;
-  scoped_refptr<EthernetService> service_;
+  ServiceRefPtr service_;
   DISALLOW_COPY_AND_ASSIGN(Ethernet);
 };