clovis: Failed requests have no timings, don't crash in the serialization.

tools/android/loading/request_track.py

 # Copyright (c) 2016 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.
 
 """The request data track.
 
 When executed, parses a JSON dump of DevTools messages.
 """
 
 import bisect
@@ skipping 202 matching lines @@
       return None
     return self.start_msec + self.timing.LargestOffset()
 
   def _TimestampOffsetFromStartMs(self, timestamp):
     assert self.timing.request_time != -1
     request_time = self.timing.request_time
     return (timestamp - request_time) * 1000
 
   def ToJsonDict(self):
     result = copy.deepcopy(self.__dict__)
-    result['timing'] = self.timing.ToJsonDict()
+    result['timing'] = self.timing.ToJsonDict() if self.timing else {}
     return result
 
   @classmethod
   def FromJsonDict(cls, data_dict):
     result = Request()
     for (k, v) in data_dict.items():
       setattr(result, k, v)
     if not result.response_headers:
       result.response_headers = {}
     if result.timing:
@@ skipping 538 matching lines @@
 
 
 if __name__ == '__main__':
   import json
   import sys
   events = json.load(open(sys.argv[1], 'r'))
   request_track = RequestTrack(None)
   for event in events:
     event_method = event['method']
     request_track.Handle(event_method, event)