depot_tools: add infra_paths recipe module for infra-specific paths

recipe_modules/git/example.py

 # Copyright 2013 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 = [
   'git',
+  'infra_paths',
   'recipe_engine/path',
   'recipe_engine/platform',
   'recipe_engine/properties',
   'recipe_engine/raw_io',
   'recipe_engine/step',
 ]
 
 
 def RunSteps(api):
   url = 'https://chromium.googlesource.com/chromium/src.git'
 
   # git.checkout can optionally dump GIT_CURL_VERBOSE traces to a log file,
   # useful for debugging git access issues that are reproducible only on bots.
   curl_trace_file = None
   if api.properties.get('use_curl_trace'):
-    curl_trace_file = api.path['slave_build'].join('curl_trace.log')
+    curl_trace_file = api.infra_paths['slave_build'].join('curl_trace.log')
 
   submodule_update_force = api.properties.get('submodule_update_force', False)
   submodule_update_recursive = api.properties.get('submodule_update_recursive',
           True)
 
   # You can use api.git.checkout to perform all the steps of a safe checkout.
   retVal = api.git.checkout(
       url,
       ref=api.properties.get('revision'),
       recursive=True,
@@ skipping 40 matching lines @@
 
   if api.properties.get('cat_file', None):
     step_result = api.git.cat_file_at_commit(api.properties['cat_file'],
                                              api.properties['revision'],
                                              stdout=api.raw_io.output())
     if 'TestOutput' in step_result.stdout:
       pass  # Success!
 
   # Bundle the repository.
   api.git.bundle_create(
-        api.path['slave_build'].join('all.bundle'))
+        api.infra_paths['slave_build'].join('all.bundle'))
 
 
 def GenTests(api):
   yield api.test('basic')
   yield api.test('basic_ref') + api.properties(revision='refs/foo/bar')
   yield api.test('basic_branch') + api.properties(revision='refs/heads/testing')
   yield api.test('basic_hash') + api.properties(
       revision='abcdef0123456789abcdef0123456789abcdef01')
   yield api.test('basic_file_name') + api.properties(checkout_file_name='DEPS')
   yield api.test('basic_submodule_update_force') + api.properties(
@@ skipping 44 matching lines @@
       api.test('count-objects_with_bad_output_fails_build') +
       api.step_data(
           'count-objects',
           stdout=api.raw_io.output(api.git.count_objects_output('xxx'))) +
       api.properties(count_objects_can_fail_build=True))
   yield (
       api.test('cat-file_test') +
       api.step_data('git cat-file abcdef12345:TestFile',
                     stdout=api.raw_io.output('TestOutput')) +
       api.properties(revision='abcdef12345', cat_file='TestFile'))