Add Paths as first-class types in configs.

scripts/slave/recipe_modules/chromium_android/chromium_config.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.
 
+from slave.recipe_config_types import Path
+
 from RECIPE_MODULES.chromium import CONFIG_CTX
 
 @CONFIG_CTX(includes=['ninja', 'static_library'])
 def android_defaults(c):
   c.compile_py.default_targets=['All']
   c.gyp_env.GYP_CROSSCOMPILE = 1
   c.gyp_env.GYP_GENERATORS.add('ninja')
   c.gyp_env.GYP_GENERATOR_FLAGS['default_target'] = 'All'
   gyp_defs = c.gyp_env.GYP_DEFINES
   gyp_defs['fastbuild'] = 1
   gyp_defs['OS'] = 'android'
   gyp_defs['host_os'] = 'linux'
   gyp_defs['gcc_version'] = 46
-  gyp_defs['order_text_section'] = ['orderfiles', 'orderfile.out']
+  gyp_defs['order_text_section'] = Path(
+    'checkout', 'orderfiles', 'orderfile.out')
   gyp_defs['target_arch'] = 'arm'
-  
+
 
 @CONFIG_CTX(includes=['android_defaults', 'default_compiler', 'goma'])
 def main_builder(c):
   pass
 
 @CONFIG_CTX(includes=['android_defaults', 'clang', 'goma'])
 def clang_builder(c):
   pass
 
 @CONFIG_CTX(includes=['main_builder'])
 def component_builder(c):
   c.gyp_env.GYP_DEFINES['component'] = 'shared_library'
 
 @CONFIG_CTX(includes=['main_builder'])
 def x86_builder(c):
   c.gyp_env.GYP_DEFINES['target_arch'] = 'ia32'
 
 @CONFIG_CTX(includes=['main_builder'])
 def klp_builder(c):
   gyp_defs = c.gyp_env.GYP_DEFINES
   gyp_defs['android_sdk_version'] = 'KeyLimePie'
-  gyp_defs['android_sdk_root'] = ['third_party', 'android_tools_internal',
-                                  'sdk']
+  gyp_defs['android_sdk_root'] = Path(
+    'checkout', 'third_party', 'android_tools_internal', 'sdk')
 
 @CONFIG_CTX(includes=['main_builder'])
 def try_builder(c):
   pass
 
 @CONFIG_CTX(includes=['x86_builder', 'try_builder'])
 def x86_try_builder(c):
   pass