shill: by default, prefer ethernet over wifi

BUG=chromium-os:26529
TEST=unit tests, manual

Manual testing: ran on device, verified that a connected Ethernet service
was sorted before a connected WiFi service, and the reason for the relative
ordering was "Technology".

Change-Id: Ie23b7d2e8f2459db89762cfa2b7695b9fd9ad21e
Reviewed-on: https://gerrit.chromium.org/gerrit/16402
Commit-Ready: mukesh agrawal <quiche@chromium.org>
Reviewed-by: mukesh agrawal <quiche@chromium.org>
Tested-by: mukesh agrawal <quiche@chromium.org>
diff --git a/manager_unittest.cc b/manager_unittest.cc
index 27f49b3..a8388de 100644
--- a/manager_unittest.cc
+++ b/manager_unittest.cc
@@ -923,9 +923,8 @@
       .WillRepeatedly(Return(false));
 
   Error error;
-  manager()->SetTechnologyOrder(string(flimflam::kTypeEthernet) + "," +
-                                string(flimflam::kTypeWifi), &error);
-  EXPECT_TRUE(error.IsSuccess());
+  // Default technology ordering should favor Ethernet over WiFi.
+  manager()->SortServices();
   EXPECT_TRUE(ServiceOrderIs(mock_service1, mock_service0));
 
   manager()->SetTechnologyOrder(string(flimflam::kTypeWifi) + "," +