tools/android/loading Ignore timings for requests coming from cache

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 473 matching lines @@
     response = params['response']
     _CopyFromDictToObject(
         response, r, (('status', 'status'), ('mimeType', 'mime_type'),
                       ('fromDiskCache', 'from_disk_cache'),
                       ('fromServiceWorker', 'from_service_worker'),
                       ('protocol', 'protocol'),
                       # Actual request headers are not known before reaching the
                       # network stack.
                       ('requestHeaders', 'request_headers'),
                       ('headers', 'response_headers')))
-    # data URLs don't have a timing dict.
     timing_dict = {}
-    if r.protocol != 'data':
+    # data URLs don't have a timing dict, and timings for cached requests are
+    # stale.
+    # TODO(droger): the timestamp is inacurate, get the real timings instead.
+    if r.protocol == 'data' or r.served_from_cache:
+      timing_dict = {'requestTime': r.timestamp}
+    else:
       timing_dict = response['timing']
-    else:
-      timing_dict = {'requestTime': r.timestamp}
     r.timing = TimingFromDict(timing_dict)
     self._requests_in_flight[request_id] = (r, RequestTrack._STATUS_RESPONSE)
     self._request_id_to_response_received[request_id] = params
 
   def _DataReceived(self, request_id, params):
     (r, status) = self._requests_in_flight[request_id]
     assert (status == RequestTrack._STATUS_RESPONSE
             or status == RequestTrack._STATUS_DATA)
     offset = r._TimestampOffsetFromStartMs(params['timestamp'])
     r.data_chunks.append((offset, params['encodedDataLength']))
@@ skipping 54 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)