[autotest] Make gather_unique_dicts private

BUG=None
TEST=None

Change-Id: I418f374f7129f25fb6d218b929e6a64411555ab7
Reviewed-on: https://chromium-review.googlesource.com/420514
Commit-Ready: Allen Li <ayatane@chromium.org>
Tested-by: Allen Li <ayatane@chromium.org>
Reviewed-by: Prathmesh Prabhu <pprabhu@chromium.org>
diff --git a/frontend/afe/rpc_utils.py b/frontend/afe/rpc_utils.py
index 5b9a000..eef18e0 100644
--- a/frontend/afe/rpc_utils.py
+++ b/frontend/afe/rpc_utils.py
@@ -39,7 +39,7 @@
     """
     if (isinstance(objects, list) and len(objects) and
         isinstance(objects[0], dict) and 'id' in objects[0]):
-        objects = gather_unique_dicts(objects)
+        objects = _gather_unique_dicts(objects)
     return _prepare_data(objects)
 
 
@@ -106,7 +106,7 @@
     return response
 
 
-def gather_unique_dicts(dict_iterable):
+def _gather_unique_dicts(dict_iterable):
     """\
     Pick out unique objects (by ID) from an iterable of object dicts.
     """