Added some browsertests to PageLoadMetrics change

chrome/chrome_tests.gypi

 # Copyright 2013 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.
 {
   'variables': {
     'chrome_browser_extensions_test_support_sources': [
       # A list of sources which is shared between different browser tests.
       'browser/apps/app_browsertest_util.cc',
       'browser/apps/app_browsertest_util.h',
       'browser/extensions/browsertest_util.cc',
@@ skipping 342 matching lines @@
       'browser/metrics/metrics_service_browsertest.cc',
       'browser/net/cookie_policy_browsertest.cc',
       'browser/net/dns_probe_browsertest.cc',
       'browser/net/ftp_browsertest.cc',
       'browser/net/load_timing_browsertest.cc',
       'browser/net/nss_context_chromeos_browsertest.cc',
       'browser/net/predictor_browsertest.cc',
       'browser/net/proxy_browsertest.cc',
       'browser/net/sdch_browsertest.cc',
       'browser/net/websocket_browsertest.cc',
+      'browser/page_load_metrics/page_load_metrics_browsertest.cc',
       'browser/password_manager/password_manager_browsertest.cc',
       'browser/pdf/pdf_extension_test.cc',
       'browser/pdf/pdf_extension_test_util.cc',
       'browser/pdf/pdf_extension_test_util.h',
       'browser/plugins/plugin_power_saver_browsertest.cc',
       'browser/prefetch/prefetch_browsertest.cc',
       'browser/prefs/pref_functional_browsertest.cc',
       'browser/prefs/pref_service_browsertest.cc',
       'browser/prefs/synced_pref_change_registrar_browsertest.cc',
       'browser/prefs/tracked/pref_hash_browsertest.cc',
@@ skipping 2989 matching lines @@
             'utility',
           ],
           'sources': [
             'tools/service_discovery_sniffer/service_discovery_sniffer.cc',
             'tools/service_discovery_sniffer/service_discovery_sniffer.h',
           ],
         }]
     }],
   ],  # 'conditions'
 }