Add Paths as first-class types in configs.

scripts/slave/recipe_modules/android/config.py

Index: scripts/slave/recipe_modules/android/config.py
diff --git a/scripts/slave/recipe_modules/android/config.py b/scripts/slave/recipe_modules/android/config.py
index 711f464869a2b7ee2d7a25c5c1f8da5b96ce1d65..247a4106aa3ef7bff8194ec7c5f9b796d62068ab 100644
--- a/scripts/slave/recipe_modules/android/config.py
+++ b/scripts/slave/recipe_modules/android/config.py
@@ -4,8 +4,12 @@
 
 from slave.recipe_config import config_item_context, ConfigGroup, Single, List
 from slave.recipe_config import Static
+from slave.recipe_config_types import Path
 
 def BaseConfig(USE_MIRROR=False):
+  chromium_in_android_subpath = ('external', 'chromium_org')
+  build_path = Path('slave_build', ('android-src',))
+
   return ConfigGroup(
     lunch_flavor = Single(basestring),
     repo = ConfigGroup(
@@ -14,6 +18,13 @@ def BaseConfig(USE_MIRROR=False):
       sync_flags = List(basestring),
     ),
     USE_MIRROR = Static(bool(USE_MIRROR)),
+
+    # Path stuff
+    chromium_in_android_subpath = Static('/'.join(chromium_in_android_subpath)),
+    build_path = Static(build_path),
+    slave_chromium_in_android_path = Static(
+      build_path(*chromium_in_android_subpath)),
+    slave_android_out_path = Static(build_path('out')),
   )
 
 config_ctx = config_item_context(