Extract functions from path recipe module so that step can depend on it

scripts/slave/recipe_modules/syzygy/api.py

Index: scripts/slave/recipe_modules/syzygy/api.py
diff --git a/scripts/slave/recipe_modules/syzygy/api.py b/scripts/slave/recipe_modules/syzygy/api.py
index e5881f67e2917c890aa4af833324e97a91b26c27..6b2b422c9f153cd025d01eb3d5bd08ba003cc137 100644
--- a/scripts/slave/recipe_modules/syzygy/api.py
+++ b/scripts/slave/recipe_modules/syzygy/api.py
@@ -293,7 +293,7 @@ PATCH=1
   def clobber_metrics(self):
     """Returns a step that clobbers an existing metrics file."""
     # TODO(chrisha): Make this whole thing use the JSON output mechanism.
-    return self.m.path.rmwildcard('metrics.csv', self.output_dir)
+    return self.m.file.rmwildcard('metrics.csv', self.output_dir)
 
   def archive_metrics(self):
     """Returns a step that archives any metrics collected by the unittests.