Try to use bot_update in Skia repo recipes

infra/bots/recipes/swarm_trigger.py

 # Copyright 2016 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.
 
 
 # Recipe module for Skia Swarming trigger.
 
 
 import os
 import json
 
 
 DEPS = [
   'build/file',
   'build/gsutil',
   'builder_name_schema',
   'core',
+  'depot_tools/bot_update',
   'depot_tools/depot_tools',
   'depot_tools/git',
-  'depot_tools/tryserver',
   'recipe_engine/json',
   'recipe_engine/path',
   'recipe_engine/properties',
   'recipe_engine/python',
   'recipe_engine/raw_io',
   'recipe_engine/step',
   'recipe_engine/time',
   'run',
   'swarming',
   'vars',
@@ skipping 735 matching lines @@
   test += api.path.exists(*paths)
 
   return test
 
 
 def GenTests(api):
   for mastername, slaves in TEST_BUILDERS.iteritems():
     for slavename, builders_by_slave in slaves.iteritems():
       for builder in builders_by_slave:
         yield test_for_bot(api, builder, mastername, slavename)