Add an MB entry for a missing CrOS builder.

tools/mb/mb_config.pyl

 # Copyright 2015 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.
 
 {
   # This is a map of buildbot master names -> buildbot builder names ->
   # config names (where each config name is a key in the 'configs' dict,
   # below). MB uses this dict to look up which config to use for a given bot.
   'masters': {
     'chromeos.chrome': {
       'amd64-generic Trusty (Informational)': 'cros_chrome_sdk_gn',
+      'Linux ChromeOS Buildspec Tests': 'swarming_chromeos_gn_release_bot',
     },
 
     # Take care when changing any of these builders to ensure that you do not
     # include a configuration with 'chrome_with_codecs' since these builders
     # generated publicly advertised non-Official builds which are not allowed
     # to have proprietary codecs enabled.
     'chromium': {
       'Android': 'android_without_codecs_gn_release_bot_minimal_symbols',
       'Linux x64': 'noswarming_gn_release_bot',
       'Mac': 'noswarming_gn_release_bot_mac_strip',
@@ skipping 2499 matching lines @@
     },
 
     'drfuzz': { 'gn_args': 'use_drfuzz=true' },
 
     'drmemory': {
       'gn_args': 'is_component_build=true enable_iterator_debugging=false',
       'gyp_defines': 'component=shared_library build_for_tool=drmemory',
     },
   },
 }