Fix lint errors to enable stricter PyLint rules

tools-webrtc/gtest-parallel-wrapper.py

 #!/usr/bin/env python
 
 # Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
 #
 # Use of this source code is governed by a BSD-style license
 # that can be found in the LICENSE file in the root of the source
 # tree. An additional intellectual property rights grant can be found
 # in the file PATENTS.  All contributing project authors may
 # be found in the AUTHORS file in the root of the source tree.
 
+# pylint: disable=invalid-name
 """
 This script acts as an interface between the Chromium infrastructure and
 gtest-parallel, renaming options and translating environment variables into
 flags. Developers should execute gtest-parallel directly.
 
 In particular, this translates the GTEST_SHARD_INDEX and GTEST_TOTAL_SHARDS
 environment variables to the --shard_index and --shard_count flags, and renames
 the --isolated-script-test-output flag to --dump_json_test_results.
 
 Note that the flags unprocessed by this script will passed as arguments to the
@@ skipping 15 matching lines @@
       --unprocessed_arg_1
       --unprocessed_arg_2
 """
 
 import argparse
 import os
 import subprocess
 import sys
 
 
-def cat_files(file_list, output_file):
+def CatFiles(file_list, output_file):
   with open(output_file, 'w') as output_file:
     for filename in file_list:
       with open(filename) as input_file:
         output_file.write(input_file.read())
       os.remove(filename)
 
 
 def main():
   # Ignore '--'. Options unprocessed by this script will be passed to the test
   # as arguments.
@@ skipping 63 matching lines @@
   sys.stdout.flush()
 
   exit_code = subprocess.call(command, env=test_env, cwd=os.getcwd())
 
   for test_status in 'passed', 'failed', 'interrupted':
     logs_dir = os.path.join(options.output_dir, test_status)
     if not os.path.isdir(logs_dir):
       continue
     logs = [os.path.join(logs_dir, log) for log in os.listdir(logs_dir)]
     log_file = os.path.join(options.output_dir, '%s-tests.log' % test_status)
-    cat_files(logs, log_file)
+    CatFiles(logs, log_file)
     os.rmdir(logs_dir)
 
   return exit_code
 
 
 if __name__ == '__main__':
   sys.exit(main())