Add config for Linux layout test try bot with --enable-slimming-paint-v2.

scripts/slave/recipe_modules/chromium_tests/trybots.py

 # 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.
 
 from recipe_engine.types import freeze
 
 
 def simple_bot(bot_id, analyze_mode=None):
   return {
     'bot_ids': [bot_id],
@@ skipping 326 matching lines @@
         'tester': 'Linux TSan Tests',
       }),
       'linux_chromium_cfi_rel_ng': simple_bot({
         'mastername': 'chromium.fyi',
         'buildername': 'CFI Linux',
       }),
       'linux_site_isolation': simple_bot({
         'mastername': 'chromium.fyi',
         'buildername': 'Site Isolation Linux',
       }),
+      'linux_layout_tests_slimming_paint_v2': simple_bot({
+        'mastername': 'chromium.fyi',
+        'buildername': 'WebKit Linux slimming_paint_v2 Dummy Builder',
+      }),
       # Optional GPU bots.
       'linux_optional_gpu_tests_rel': {
         'bot_ids': [
           {
             'mastername': 'chromium.gpu.fyi',
             'buildername': 'GPU Linux Builder',
             'tester': 'Optional Linux Release (NVIDIA)',
           },
         ],
       },
@@ skipping 198 matching lines @@
         'mastername': 'client.v8.fyi',
         'buildername': 'V8 Linux GN',
       }),
       'v8_android_chromium_gn_dbg': simple_bot({
         'mastername': 'client.v8.fyi',
         'buildername': 'V8 Android GN (dbg)',
       }),
     },
   },
 })