Update DevTools Tracing.Start to accept trace config as a parameter

content/content_tests.gypi

 # Copyright (c) 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': {
     'layouttest_support_content_sources': [
       'public/test/layouttest_support.h',
       'public/test/nested_message_pump_android.cc',
       'public/test/nested_message_pump_android.h',
@@ skipping 374 matching lines @@
       'browser/compositor/software_browser_compositor_output_surface_unittest.cc',
       'browser/compositor/software_output_device_ozone_unittest.cc',
       'browser/database_quota_client_unittest.cc',
       'browser/database_tracker_unittest.cc',
       'browser/database_util_unittest.cc',
       'browser/databases_table_unittest.cc',
       'browser/device_sensors/data_fetcher_shared_memory_base_unittest.cc',
       'browser/device_sensors/sensor_manager_android_unittest.cc',
       'browser/device_sensors/sensor_manager_chromeos_unittest.cc',
       'browser/devtools/devtools_manager_unittest.cc',
+      'browser/devtools/protocol/tracing_handler_unittest.cc',
       'browser/devtools/shared_worker_devtools_manager_unittest.cc',
       'browser/dom_storage/dom_storage_area_unittest.cc',
       'browser/dom_storage/dom_storage_context_impl_unittest.cc',
       'browser/dom_storage/dom_storage_database_unittest.cc',
       'browser/dom_storage/session_storage_database_unittest.cc',
       'browser/download/base_file_unittest.cc',
       'browser/download/download_file_unittest.cc',
       'browser/download/download_item_impl_unittest.cc',
       'browser/download/download_manager_impl_unittest.cc',
       'browser/download/file_metadata_unittest_linux.cc',
@@ skipping 1844 matching lines @@
                   'content_unittests_apk.isolate',
                 ],
               },
             ],
           },
         ],
       ],
     }],
   ],
 }