Add a MailNotifier that notifies chrome-security-sheriff@grotations.appspotmail.com for LKGR builds.

masters/master.chromium.lkgr/master.cfg

Index: masters/master.chromium.lkgr/master.cfg
diff --git a/masters/master.chromium.lkgr/master.cfg b/masters/master.chromium.lkgr/master.cfg
index 52eac099fc6b1c0321cfd15bf7f16c5272edba7a..34e5c38323229330ca9529d7f595c8acdfd8c744 100644
--- a/masters/master.chromium.lkgr/master.cfg
+++ b/masters/master.chromium.lkgr/master.cfg
@@ -2,6 +2,8 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+from buildbot.status.mail import MailNotifier
+
 from master import master_utils
 from master import slaves_list
 
@@ -46,3 +48,11 @@ master_utils.AutoSetupMaster(c, ActiveMaster,
     templates=['../master.chromium/templates'],
     tagComparator=c['change_source'][0].comparator,
     enable_http_status_push=ActiveMaster.is_production_host)
+
+c['status'].append(MailNotifier(
+    fromaddr=ActiveMaster.from_address,
+    mode='problem',
+    relayhost=config.Master.smtp,
+    subject='LKGR build failure on %(builder)s',
+    extraRecipients=['chrome-security-sheriff@grotations.appspotmail.com'],
+    sendToInterestedUsers=False))