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

scripts/slave/recipes/blink_android_trybot.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',
   'path',
   'platform',
   'properties',
   'step',
   'tryserver',
 ]
 
 def GenSteps(api):
   mastername = api.properties['mastername']
@@ skipping 10 matching lines @@
   # TODO(dpranke): crbug.com/348435. We need to figure out how to separate
   # out the retry and recovery logic from the rest of the recipe.
 
   step_result = api.bot_update.ensure_checkout()
   # The first time we run bot update, remember if bot_update mode is on or off.
   bot_update_mode = step_result.json.output['did_run']
   if not bot_update_mode:
     try:
       api.gclient.checkout(revert=True)
     except api.step.StepFailure:
-      api.path.rmcontents('slave build directory',
+      api.file.rmcontents('slave build directory',
                                 api.path['slave_build'])
       api.gclient.checkout(revert=False)
     api.tryserver.maybe_apply_issue()
 
   api.chromium.runhooks()
 
   api.chromium.run_mb(mastername, buildername)
 
   step_result = None
   try:
     step_result = api.chromium.compile()
   except api.step.StepFailure:
-    api.path.rmcontents('slave build directory', api.path['slave_build'])
+    api.file.rmcontents('slave build directory', api.path['slave_build'])
     if bot_update_mode:
       api.bot_update.ensure_checkout(suffix='clean')
     else:
       api.gclient.checkout(revert=False)
       api.tryserver.maybe_apply_issue()
     api.chromium.runhooks()
     api.chromium.run_mb(api.properties['mastername'],
                         api.properties['buildername'])
     api.chromium.compile()
 
@@ skipping 22 matching lines @@
       api.platform.name('linux')
   )
 
 
   yield (
       api.test('bot_update_on') +
       api.properties.tryserver(buildername='fake_trybot_buildername',
                                mastername='bot_update.always_on') +
       api.step_data('compile', retcode=1)
   )