Extract functions from path recipe module so that step can depend on it

scripts/slave/recipes/infra/publish_tarball.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.
 
 DEPS = [
   'bot_update',
   'chromium',
+  'file',
   'gclient',
   'gsutil',
   'omahaproxy',
   'path',
   'platform',
   'properties',
   'python',
   'raw_io',
   'trigger',
 ]
 
 
 def export_tarball(api, args, source, destination):
   try:
     temp_dir = api.path.mkdtemp('export_tarball')
     api.python(
         'export_tarball',
         api.chromium.resource('export_tarball.py'),
         args,
         cwd=temp_dir)
     api.gsutil.upload(
         api.path.join(temp_dir, source),
         'chromium-browser-official',
         destination)
   finally:
-    api.path.rmtree('temp dir', temp_dir)
+    api.file.rmtree('temp dir', temp_dir)
 
 
 def GenSteps(api):
   if 'version' not in api.properties:
     ls_result = api.gsutil(['ls', 'gs://chromium-browser-official/'],
                            stdout=api.raw_io.output()).stdout
     missing_releases = set()
     # TODO(phajdan.jr): find better solution than hardcoding version number.
     # We do that currently (carryover from a solution this recipe is replacing)
     # to avoid running into errors with older releases.
@@ skipping 30 matching lines @@
     api.properties.generic(version='38.0.2125.122') +
     api.platform('linux', 64)
   )
 
   yield (
     api.test('trigger') +
     api.properties.generic() +
     api.platform('linux', 64) +
     api.step_data('gsutil ls', stdout=api.raw_io.output(''))
   )