Refactor the way that TestApi works so that it is actually useful.

scripts/slave/recipe_modules/chromite/example.py

Index: scripts/slave/recipe_modules/chromite/example.py
diff --git a/scripts/slave/recipe_modules/chromite/example.py b/scripts/slave/recipe_modules/chromite/example.py
index 3a2ec3d25bc57f62e821365ed9e96261142d237f..a385c3c5b0f7b03cebe53639aacf835dcafe9edf 100644
--- a/scripts/slave/recipe_modules/chromite/example.py
+++ b/scripts/slave/recipe_modules/chromite/example.py
@@ -18,8 +18,6 @@ def GenSteps(api):
   )
 
 
-def GenTests(_api):
+def GenTests(api):
   for bits in (32, 64):
-    yield 'basic_%s' % bits, {
-      'properties': {'TARGET_BITS': bits},
-    }
+    yield api.Test('basic_%s' % bits) + api.Properties(TARGET_BITS=bits)