build: use class path bases, not strings

scripts/slave/recipe_modules/syzygy/api.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.
 
 import ast
 import os
 import re
 
 from recipe_engine import recipe_api
 
@@ skipping 32 matching lines @@
 PATCH=1
 """
 
   def __init__(self, *args, **kwargs):
     super(SyzygyApi, self).__init__(*args, **kwargs)
     # This is populated by the first call to 'version'.
     self._version = None
     # This is populated by the sync step.
     self._revision = None
 
+  def get_config_defaults(self):
+    return {
+      'CHECKOUT_PATH': self.m.path['checkout'],
+    }
+
   @property
   def build_dir(self):
     """Returns the build directory for the project."""
     build_tool = self.m.chromium.c.compile_py.build_tool
     if build_tool == 'ninja':
       return self.m.path['checkout'].join('out')
 
   @property
   def output_dir(self):
     """Returns the configuration-specific output directory for the project."""
@@ skipping 256 matching lines @@
             '--overwrite',
             '--verbose']
     return self.m.python('download_binaries', get_syzygy_binaries_py, args)
 
   def smoke_test(self):
     """Returns a step that launches the smoke test script."""
     smoke_test_py = self.internal_scripts_dir.join('smoke_test.py')
     build_dir = self.m.path['checkout'].join('build')
     args = ['--verbose', '--build-dir', build_dir]
     return self.m.python('smoke_test', smoke_test_py, args)