Fix misnamed method.

In cl/190784 I missed this other call to get_aps_by_hostnames.

TEST=Ran it
BUG=None

Change-Id: I75987adff1ae5b2bfde6d3c4fead00a4f61d8409
Reviewed-on: https://chromium-review.googlesource.com/191138
Tested-by: Kris Rambish <krisr@chromium.org>
Reviewed-by: Jason Abele <jabele@chromium.org>
Commit-Queue: Kris Rambish <krisr@chromium.org>
diff --git a/server/cros/chaos_ap_configurators/ap_configurator_factory.py b/server/cros/chaos_ap_configurators/ap_configurator_factory.py
index e3931e1..ce0dbac 100644
--- a/server/cros/chaos_ap_configurators/ap_configurator_factory.py
+++ b/server/cros/chaos_ap_configurators/ap_configurator_factory.py
@@ -390,8 +390,8 @@
             matching_aps = self._get_aps_by_configurator_type(
                            spec.configurator_type, matching_aps)
         if spec.hostnames is not None:
-            matching_aps = self._get_aps_by_hostnames(spec.hostnames,
-                                                      ap_list=matching_aps)
+            matching_aps = self.get_aps_by_hostnames(spec.hostnames,
+                                                     ap_list=matching_aps)
         if pre_configure:
             for ap in matching_aps:
                 ap.set_using_ap_spec(spec)