Add entry to mb_config.pyl for Linux layout test try bot with flag --enable-slimming-paint-v2.

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': {
     # Take care when changing any of these builders to ensure that you do not
@@ skipping 757 matching lines @@
       'linux_chromium_variable_32': 'findit',
       'linux_chromium_variable_chrome': 'findit',
       'linux_chromium_variable_clobber': 'findit',
       'linux_chromium_variable_32_chrome': 'findit',
       'linux_chromium_variable_32_clobber': 'findit',
       'linux_chromium_webkit_asan_variable': 'findit',
       'linux_chromium_webkit_leak_variable': 'findit',
       'linux_chromium_webkit_msan_variable': 'findit',
       'linux_chromium_webkit_variable': 'findit',
       'linux_chromiumos_full_variable': 'findit',
+
+      # This is 'release_bot' rather than 'release_trybot' because
+      # 'release_trybot' includes 'dcheck_always_on', which might cause
+      # some layout test results to be different than for normal release
+      # builds (and we only store baselines for release builds).
+      'linux_layout_tests_slimming_paint_v2': 'swarming_gn_release_bot',
+
+      'linux_nacl_sdk_build': 'gn_release_bot',
       'linux_nacl_sdk': 'gn_release_bot',
-      'linux_nacl_sdk_build': 'gn_release_bot',
       'linux_optional_gpu_tests_rel':
         'swarming_gpu_fyi_tests_gn_release_trybot',
       'linux_site_isolation': 'gn_release_trybot',
       'linux_upload_clang': 'gn_release_bot',
     },
 
     'tryserver.chromium.mac': {
       'ios-device': 'ios_gyp',
       'ios-device-gn': 'ios_gn',
       'ios-simulator': 'ios_gyp',
@@ skipping 1520 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',
     },
   },
 }