Revert of Extend chromium_tests trigger to work across masters.

scripts/slave/recipe_modules/chromium_tests/bot_config_and_test_db.py

 # Copyright 2016 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 copy
 
 from recipe_engine.types import freeze
 
 
@@ skipping 102 matching lines @@
       if bot_id.get('tester'):
         bot_config = bot_db.get_bot_config(
             bot_id['mastername'], bot_id['tester'])
         tests.extend([copy.deepcopy(t) for t in bot_config.get('tests', [])])
 
     tests_including_triggered = list(tests)
     for bot_id in self._bot_ids:
       bot_config = bot_db.get_bot_config(
           bot_id['mastername'], bot_id['buildername'])
 
-      for _, _, test_bot in bot_db.bot_configs_matching_parent_buildername(
+      for _, test_bot in bot_db.bot_configs_matching_parent_buildername(
           bot_id['mastername'], bot_id['buildername']):
         tests_including_triggered.extend(test_bot.get('tests', []))
 
     return tests, tests_including_triggered
 
   def get_compile_targets(self, chromium_tests_api, bot_db, tests):
     compile_targets = set()
     for bot_id in self._bot_ids:
       bot_config = bot_db.get_bot_config(
           bot_id['mastername'], bot_id['buildername'])
@@ skipping 41 matching lines @@
                              'test_spec': test_spec }
 
   def get_bot_config(self, mastername, buildername):
     return self._db[mastername]['master_dict'].get('builders', {}).get(
         buildername)
 
   def get_master_settings(self, mastername):
     return self._db[mastername]['master_dict'].get('settings', {})
 
   def bot_configs_matching_parent_buildername(
-      self, parent_mastername, parent_buildername):
+      self, mastername, parent_buildername):
     """A generator of all the (buildername, bot_config) tuples whose
     parent_buildername is the passed one on the given master.
     """
-    for mastername, master_config in self._db.iteritems():
-      master_dict = self._db[parent_mastername]['master_dict']
-      for buildername, bot_config in master_dict.get(
-          'builders', {}).iteritems():
-        master_matches = (bot_config.get('parent_mastername', mastername) ==
-                          parent_mastername)
-        builder_matches = (bot_config.get('parent_buildername') ==
-                           parent_buildername)
-        if master_matches and builder_matches:
-          yield mastername, buildername, bot_config
+    for buildername, bot_config in self._db[mastername]['master_dict'].get(
+        'builders', {}).iteritems():
+      if bot_config.get('parent_buildername') == parent_buildername:
+        yield buildername, bot_config
 
   def get_test_spec(self, mastername, buildername):
     return self._db[mastername]['test_spec'].get(buildername, {})