[Clean-up] Add a PRESUBMIT.py script for the proximity_auth component.

The script currently just verifies that all changes are "git cl format" clean.

BUG=none
TEST=none
R=tengs@chromium.org

Review URL: https://codereview.chromium.org/611673002

Cr-Commit-Position: refs/heads/master@{#297089}

components/proximity_auth/PRESUBMIT.py

+# Copyright 2014 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+"""Top-level presubmit script for the proximity_auth component.
+
+See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts
+for more details about the presubmit API built into depot_tools.
+"""
+
+def CheckChangeOnUpload(input_api, output_api):
+  return input_api.canned_checks.CheckPatchFormatted(input_api, output_api)