Update tracing WATCHLISTS to track base/trace_event

WATCHLISTS

 # Copyright (c) 2012 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.
 
 # Watchlist Rules
 # Refer: http://dev.chromium.org/developers/contributing-code/watchlists
 
 # IMPORTANT: The regular expression filepath is tested against each path using
 # re.search, so it is not usually necessary to add .*.
 
@@ skipping 687 matching lines @@
                   '|components/timers/'
     },
     'tools': {
       'filepath': 'tools/',
     },
     'tools_emacs': {
       'filepath': 'tools/emacs/',
     },
     'tracing': {
       'filepath': 'base/debug/trace_event.*'\
+                  '|base/trace_event/'\
                   '|content/browser/tracing/'\
                   '|components/tracing/'
     },
     'ui_compositor': {
       'filepath': 'ui/compositor/layer\.|'\
                   'ui/compositor/layer_unittest|'\
                   'ui/compositor/compositor',
     },
     'ui_resources': {
       'filepath': 'ui/resources/'\
@@ skipping 315 matching lines @@
                      'mcasas+watch@chromium.org',
                      'posciak+watch@chromium.org'],
     'website_settings': ['markusheintz@chromium.org'],
     'windows_sandboxing': ['wfh+watch@chromium.org'],
     'worker': ['jam@chromium.org'],
     'x11': ['derat+watch@chromium.org',
             'sadrul@chromium.org',
             'yusukes+watch@chromium.org'],
   },
 }