Improve USB device reset logic

PRESUBMIT.py

 # Copyright (c) 2012 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.
 
 import json
 import os
@@ skipping 453 matching lines @@
           (affected_file.LocalPath(), parse_error)))
   return results
 
 
 def _RunPythonTests(input_api, output_api):
   def Join(*args):
     return input_api.os_path.join(input_api.PresubmitLocalPath(), *args)
 
   test_directories = [
       Join('webrtc', 'tools', 'py_event_log_analyzer'),
+      Join('webrtc', 'tools'),
       Join('webrtc', 'audio', 'test', 'unittests'),
   ] + [
       root for root, _, files in os.walk(Join('tools-webrtc'))
       if any(f.endswith('_test.py') for f in files)
   ]
 
   tests = []
   for directory in test_directories:
     tests.extend(
       input_api.canned_checks.GetUnitTestsInDirectory(
@@ skipping 113 matching lines @@
       input_api, output_api))
   results.extend(input_api.canned_checks.CheckChangeHasDescription(
       input_api, output_api))
   results.extend(_CheckChangeHasBugField(input_api, output_api))
   results.extend(input_api.canned_checks.CheckChangeHasTestField(
       input_api, output_api))
   results.extend(input_api.canned_checks.CheckTreeIsOpen(
       input_api, output_api,
       json_url='http://webrtc-status.appspot.com/current?format=json'))
   return results