Add a new buildbot-tool generator for master configs

scripts/tools/buildbot_tool_templates/master.cfg

Index: scripts/tools/buildbot_tool_templates/master.cfg
diff --git a/masters/master.client.mojo/master.cfg b/scripts/tools/buildbot_tool_templates/master.cfg
similarity index 77%
copy from masters/master.client.mojo/master.cfg
copy to scripts/tools/buildbot_tool_templates/master.cfg
index 06463a3004b65309d5f15e19de82a3fc289ac1c2..de1fd56a6e48964c867b48a9924903f69ae90680 100644
--- a/masters/master.client.mojo/master.cfg
+++ b/scripts/tools/buildbot_tool_templates/master.cfg
@@ -2,7 +2,10 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+# This file is used by scripts/tools/buildbot-tool to generate master configs.
+
 # These modules come from scripts/master, which must be in the PYTHONPATH.
+from master import gitiles_poller
 from master import master_utils
 from master import slaves_list
 from master.factory import annotator_factory
@@ -11,7 +14,7 @@ from buildbot.status.mail import MailNotifier
 
 import config
 import master_site_config
-ActiveMaster = master_site_config.Mojo
+ActiveMaster = master_site_config.%(master_classname)s
 
 m_annotator = annotator_factory.AnnotatorFactory()
 
@@ -21,34 +24,18 @@ c['schedulers'] = []
 c['builders'] = []
 c['status'] = []
 
-builders = ['Mojo Linux',
-            'Mojo Linux (dbg)',
-            'Mojo Linux ASan',
-            'Mojo Android Builder',
-            'Mojo Android Builder (dbg)',
-            'Mojo Android Builder Tests (dbg)',
-            'Mojo ChromeOS Builder',
-            'Mojo ChromeOS Builder (dbg)',
-            'Mojo Linux Perf']
-
-for builder_name in builders:
-  c['builders'].append({
-    'name': builder_name,
-    'factory': m_annotator.BaseFactory('mojo'),
-    'slavebuilddir': 'mojo',
-  })
+%(builders_block)s
 
 config.DatabaseSetup(c, require_dbconfig=ActiveMaster.is_production_host)
 
-import master_source_cfg
-
-master_source_cfg.Update(config, ActiveMaster, c)
+c['change_source'].append(gitiles_poller.GitilesPoller(
+    '%(git_repo_url)s'))
 
 c['schedulers'].extend([
     SingleBranchScheduler(name='source',
                           branch='master',
                           treeStableTimer=60,
-                          builderNames=builders)
+                          builderNames=[b['name'] for b in c['builders']])
     ])
 
 c['logCompressionLimit'] = False
@@ -59,7 +46,7 @@ c['buildbotURL'] = ActiveMaster.buildbot_url
 
 # Associate the slaves to the manual builders. The configuration is in
 # slaves.cfg.
-slaves = slaves_list.SlavesList('slaves.cfg', 'Mojo')
+slaves = slaves_list.SlavesList('slaves.cfg', '%(master_classname)s')
 for builder in c['builders']:
   builder['slavenames'] = slaves.GetSlavesName(builder=builder['name'])