Support variable substitution and tryserver- and waterfall-only cmd line args.

scripts/slave/recipe_modules/chromium_tests/bot_config_and_test_db.py

Index: scripts/slave/recipe_modules/chromium_tests/bot_config_and_test_db.py
diff --git a/scripts/slave/recipe_modules/chromium_tests/bot_config_and_test_db.py b/scripts/slave/recipe_modules/chromium_tests/bot_config_and_test_db.py
index 11ea849c519627974450d586e92acd60cc2ce5d5..4b416a55a543aa3739f271ab3d1f11d4a714e1c6 100644
--- a/scripts/slave/recipe_modules/chromium_tests/bot_config_and_test_db.py
+++ b/scripts/slave/recipe_modules/chromium_tests/bot_config_and_test_db.py
@@ -70,7 +70,7 @@ class BotConfig(object):
       return {}
     return chromium_tests_api.read_test_spec(chromium_tests_api.m, test_spec_file)
 
-  def initialize_bot_db(self, chromium_tests_api, bot_db):
+  def initialize_bot_db(self, chromium_tests_api, bot_db, bot_update_step):
     # TODO(phajdan.jr): Make this work for more than 1 bot.
     assert len(self._bot_ids) == 1
 
@@ -103,7 +103,8 @@ class BotConfig(object):
               # Above should remove the need to get bot_config and buildername
               # in this method.
               bot_config.get('enable_swarming', False),
-              scripts_compile_targets, builder_dict.get('test_generators', [])
+              scripts_compile_targets, builder_dict.get('test_generators', []),
+              bot_update_step
           ))
 
     bot_db._add_master_dict_and_test_spec(