Break config_default into master_site_configs.

masters/master.chromium.chrome/master.cfg

 # Copyright (c) 2012 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.
 
 from buildbot.changes import svnpoller
 from buildbot.scheduler import Scheduler
 
 # These modules come from scripts/master, which must be in the PYTHONPATH.
 from master import build_utils
 from master import master_utils
 from master import slaves_list
 
 from master.factory import chromium_factory
 
 # These modules come from scripts/common, which must be in the PYTHONPATH.
 import config
+import master_site_config
 
-ActiveMaster = config.Master.ChromiumChrome
+ActiveMaster = master_site_config.ChromiumChrome
 
 # This is the dictionary that the buildmaster pays attention to. We also use
 # a shorter alias to save typing.
 c = BuildmasterConfig = {}
 
 config.DatabaseSetup(c, require_dbconfig=ActiveMaster.is_production_host)
 
 ####### CHANGESOURCES
 
 # the 'change_source' list tells the buildmaster how it should find out about
@@ skipping 251 matching lines @@
 # Adds common status and tools to this master.
 master_utils.AutoSetupMaster(c, ActiveMaster,
     public_html='../master.chromium/public_html',
     templates=['../master.chromium/templates'],
     enable_http_status_push=ActiveMaster.is_production_host)
 
 ####### PROJECT IDENTITY
 
 # Buildbot master url:
 c['buildbotURL'] = 'http://build.chromium.org/buildbot/chromium.chrome/'