Use gitiles_poller to poll chromium LKGR branch on Dr. Memory LKGR bots

masters/master.chromium.fyi/master_win_drmemory_cfg.py

 # Copyright 2014 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 master import gitiles_poller
 from master import master_config
 from master import master_utils
 from master.factory import chromium_factory
 
 import master_site_config
 ActiveMaster = master_site_config.ChromiumFYI
 
 defaults = {}
 
 helper = master_config.Helper(defaults)
@@ skipping 56 matching lines @@
                         'target_arch=x64'),
         'GYP_GENERATORS': 'ninja',
       },
       'late_cf_archive_build': ActiveMaster.is_production_host,
       'cf_archive_name': 'drmemory_x64',
       'gs_acl': 'public-read',
       'gs_bucket': 'gs://chromium-browser-drfuzz/chromium_win64',
     }))
 
 def Update(_update_config, _active_master, c):
+  lkgr_poller = gitiles_poller.GitilesPoller(
+    'https://chromium.googlesource.com/chromium/src',
+    branches=['lkgr'])
+  c['change_source'].append(lkgr_poller)
   return helper.Update(c)