Generate trace header/footer in tracing consumer instead of service

sky/tools/skydb

 #!/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.
 
 from skypy.skyserver import SkyServer
 import argparse
 import json
 import logging
 import os
@@ skipping 338 matching lines @@
         # TODO(eseidel): Does not work for android.
         mojo_map_path = "/tmp/mojo_shell.%d.maps" % self.pids['mojo_shell_pid']
         with open(mojo_map_path, 'r') as maps_file:
             lines = maps_file.read().strip().split('\n')
             return dict(map(lambda line: line.split(' '), lines))
 
     def stop_tracing_command(self, args):
         file_name = args.file_name
         trace = self._send_command_to_sky('/stop_tracing').content
         with open(file_name, "wb") as trace_file:
+            trace_file.write('{"traceEvents":[')
             trace_file.write(trace)
+            trace_file.write(']}')
         print "Trace saved in %s" % file_name
 
     def stop_profiling_command(self, args):
         self._run_basic_command('/stop_profiling')
         mojo_map = self._read_mojo_map()
 
         # TODO(eseidel): We should have a helper for resolving urls, etc.
         remote_server_port = self.pids.get('remote_sky_server_port', self.pids['sky_server_port'])
         build_dir_url = SkyServer.url_for_path(
             remote_server_port,
@@ skipping 244 matching lines @@
         load_parser.set_defaults(func=self.load_command)
 
         args = parser.parse_args()
         args.func(args)
 
         self._write_pid_file(PID_FILE_PATH, self.pids)
 
 
 if __name__ == '__main__':
     SkyDebugger().main()