[Tracing Clock Sync] Add TracingAgent interface in Chrome

tools/gn/bootstrap/bootstrap.py

 #!/usr/bin/env python
 # 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.
 
 """Bootstraps gn.
 
 It is done by first building it manually in a temporary directory, then building
 it with its own BUILD.gn to the final destination.
 """
@@ skipping 249 matching lines @@
       'base/trace_event/process_memory_totals_dump_provider.cc',
       'base/trace_event/trace_buffer.cc',
       'base/trace_event/trace_config.cc',
       'base/trace_event/trace_event_argument.cc',
       'base/trace_event/trace_event_impl.cc',
       'base/trace_event/trace_event_memory_overhead.cc',
       'base/trace_event/trace_event_synthetic_delay.cc',
       'base/trace_event/trace_log.cc',
       'base/trace_event/trace_log_constants.cc',
       'base/trace_event/trace_sampling_thread.cc',
+      'base/trace_event/tracing_agent.cc',
       'base/tracked_objects.cc',
       'base/tracking_info.cc',
       'base/values.cc',
       'base/vlog.cc',
   ])
 
   if is_posix:
     static_libraries['base']['sources'].extend([
         'base/base_paths_posix.cc',
         'base/debug/debugger_posix.cc',
@@ skipping 171 matching lines @@
     cmd.append('-v')
   cmd.append('gn')
   check_call(cmd)
 
   if not options.debug:
     check_call(['strip', os.path.join(build_dir, 'gn')])
 
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv[1:]))