recipe engine: extract infra-specific paths out of the engine

recipe_modules/path/example.py

Index: recipe_modules/path/example.py
diff --git a/recipe_modules/path/example.py b/recipe_modules/path/example.py
index 429b2890791b125c28a05bfe09bc6eae4951c979..2c1d2666bb37da387385952ed82b9788e8388997 100644
--- a/recipe_modules/path/example.py
+++ b/recipe_modules/path/example.py
@@ -12,7 +12,7 @@ DEPS = [
 from recipe_engine.config_types import Path
 
 def RunSteps(api):
-  api.step('step1', ['/bin/echo', str(api.path['slave_build'].join('foo'))])
+  api.step('step1', ['/bin/echo', str(api.path['tmp'].join('foo'))])
 
   # module.resource(...) demo.
   api.step('print resource',
@@ -26,7 +26,7 @@ def RunSteps(api):
   dynamic_path = Path('[CHECKOUT]', 'jerky')
 
   assert 'checkout' not in api.path
-  api.path['checkout'] = api.path['slave_build'].join('checkout')
+  api.path['checkout'] = api.path['tmp'].join('checkout')
   assert 'checkout' in api.path
 
   api.step('checkout path', ['/bin/echo', dynamic_path])
@@ -34,12 +34,12 @@ def RunSteps(api):
   # Methods from python os.path are available via api.path.
   # For testing, we asserted that this file existed in the test description
   # below.
-  assert api.path.exists(api.path['slave_build'])
+  assert api.path.exists(api.path['tmp'])
 
   temp_dir = api.path.mkdtemp('kawaab')
   assert api.path.exists(temp_dir)
 
-  file_path = api.path['slave_build'].join('new_file')
+  file_path = api.path['tmp'].join('new_file')
   abspath = api.path.abspath(file_path)
   api.path.assert_absolute(abspath)
 
@@ -53,16 +53,4 @@ def GenTests(api):
   for platform in ('linux', 'win', 'mac'):
     yield (api.test(platform) + api.platform.name(platform) +
            # Test when a file already exists
-           api.path.exists(api.path['slave_build']))
-
-    # We have support for chromium swarming built in to the engine for some
-    # reason. TODO(phajdan.jr) remove it.
-    yield (api.test('%s_swarming' % platform) +
-           api.platform.name(platform) +
-           api.properties(path_config='swarming') +
-           api.path.exists(api.path['slave_build']))
-
-    yield (api.test('%s_kitchen' % platform) +
-           api.platform.name(platform) +
-           api.properties(path_config='kitchen') +
-           api.path.exists(api.path['slave_build']))
+           api.path.exists(api.path['tmp']))