Break config_default into master_site_configs.

masters/master.tryserver.webrtc/master.cfg

 #!/usr/bin/env python
 #  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
 #
 #  Use of this source code is governed by a BSD-style license
 #  that can be found in the LICENSE file in the root of the source
 #  tree. An additional intellectual property rights grant can be found
 #  in the file PATENTS.  All contributing project authors may
 #  be found in the AUTHORS file in the root of the source tree.
 
 # These modules come from scripts, which must be in the PYTHONPATH.
 from master import master_utils
 from master import slaves_list
 from master.builders_pools import BuildersPools
 from master.factory import chromium_factory
 from master.factory import webrtc_factory
 from master.try_job_http import TryJobHTTP
 from master.try_mail_notifier import TryMailNotifier
 
 import config
+import master_site_config
 
-ActiveMaster = config.Master.WebRTCTryServer
+ActiveMaster = master_site_config.WebRTCTryServer
 
 MAIL_NOTIFIER = True
 LISTEN_TO_SVN = ActiveMaster.svn_url and ActiveMaster.is_production_host
 
 # 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)
 
@@ skipping 313 matching lines @@
 c['buildCacheSize'] = 100
 
 ####### PROJECT IDENTITY
 
 # The 'projectURL' string will be used to provide a link
 # from buildbot HTML pages to your project's home page.
 c['projectURL'] = 'http://dev.chromium.org/developers/testing/try-server-usage'
 
 # Buildbot master url:
 c['buildbotURL'] = 'http://build.chromium.org/p/tryserver.webrtc/'