Update masters after the tryserver split.

ui/events/PRESUBMIT.py

 # Copyright 2014 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.
 
 """Chromium presubmit script for src/ui/events
 
 See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts
 for more details on the presubmit API built into gcl.
 """
 
 def GetPreferredTryMasters(project, change):
   tests = set(['ash_unittests',
                'aura_unittests',
                'events_unittests',
                'keyboard_unittests',
                'views_unittests'])
 
   return {
-    'tryserver.chromium': {
-      'linux_chromium_rel': tests,
+    'tryserver.chromium.linux': {
+      'linux_chromium_rel_swarming': tests,
       'linux_chromium_chromeos_rel': tests,
       'linux_chromeos_asan': tests,
+    },
+    'tryserver.chromium.win': {
       'win_chromium_compile_dbg': tests,
       'win_chromium_rel': tests,
     }
   }