WebLayer: Add presubmit script for skew tests expectations file

Bug: 1172440
Change-Id: I24a8ecf04e74c35c91a5a09b112952d038f65e00
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2941116
Reviewed-by: Robbie McElrath <rmcelrath@chromium.org>
Commit-Queue: Rakib Hasan <rmhasan@google.com>
Cr-Commit-Position: refs/heads/master@{#889489}

weblayer/browser/android/javatests/skew/PRESUBMIT.py

@@ -0,0 +1,34 @@
+# Copyright (c) 2021 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.
+
+import inspect
+import os
+import sys
+
+EXPECTATIONS_FILE = 'expectations.txt'
+
+
+def _MaybeAddTypToPath():
+    src_dir = os.path.join(
+        os.path.dirname(inspect.getfile(CheckChangeOnUpload)),
+        os.pardir, os.pardir, os.pardir, os.pardir, os.pardir)
+    typ_dir = os.path.join(src_dir, 'third_party', 'catapult',
+                           'third_party', 'typ')
+    if typ_dir not in sys.path:
+        sys.path.append(typ_dir)
+
+
+def CheckChangeOnUpload(input_api, output_api):
+    _MaybeAddTypToPath()
+    from typ.expectations_parser import TestExpectations
+
+    results = []
+    test_expectations = TestExpectations()
+    with open(EXPECTATIONS_FILE, 'r') as exp:
+        ret, errors = test_expectations.parse_tagged_list(exp.read())
+
+    if ret:
+        results.append(output_api.PresubmitError(
+            'Expectations file had the following errors: \n' + errors))
+    return results