tools/android/loading: Add support for multiple redirects.

tools/android/loading/request_dependencies_lens.py

 # Copyright 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.
 
 """Gathers and infers dependencies between requests.
 
 When executed as a script, loads a trace and outputs the dependencies.
 """
 
 import collections
@@ skipping 46 matching lines @@
 
     Args:
       request: (Request) the request we wish to get the initiator of.
 
     Returns:
       None if no dependency is found from this request, or
       (initiator (Request), blocked_request (Request), reason (str)).
     """
     reason = request.initiator['type']
     assert reason in request_track.Request.INITIATORS
-    # Redirect suffixes are added in RequestTrack.
-    if request.request_id.endswith(request_track.RequestTrack.REDIRECT_SUFFIX):
+    if reason == 'redirect':
       return self._GetInitiatingRequestRedirect(request)
     elif reason == 'parser':
       return self._GetInitiatingRequestParser(request)
     elif reason == 'script':
       return self._GetInitiatingRequestScript(request)
     else:
       assert reason == 'other'
       return self._GetInitiatingRequestOther(request)
 
   def _GetInitiatingRequestRedirect(self, request):
-    request_id = request.request_id[:request.request_id.index(
-        request_track.RequestTrack.REDIRECT_SUFFIX)]
-    assert request_id in self._requests_by_id
-    dependent_request = self._requests_by_id[request_id]
-    assert request.timing.request_time < \
-        dependent_request.timing.request_time, '.\n'.join(
-            [str(request), str(dependent_request)])
-    return (request, dependent_request, 'redirect')
+    assert request_track.Request.INITIATING_REQUEST in request.initiator
+    initiating_request_id = request.initiator[
+        request_track.Request.INITIATING_REQUEST]
+    assert initiating_request_id in self._requests_by_id
+    return (self._requests_by_id[initiating_request_id], request, 'redirect')
 
   def _GetInitiatingRequestParser(self, request):
     url = request.initiator['url']
     candidates = self._FindMatchingRequests(url, request.timing.request_time)
     if not candidates:
       return None
     initiating_request = self._FindBestMatchingInitiator(request, candidates)
     return (initiating_request, request, 'parser')
 
   def _GetInitiatingRequestScript(self, request):
@@ skipping 91 matching lines @@
 if __name__ == '__main__':
   import json
   import sys
   trace_filename = sys.argv[1]
   json_dict = json.load(open(trace_filename, 'r'))
   lens = RequestDependencyLens(
       loading_trace.LoadingTrace.FromJsonDict(json_dict))
   depedencies = lens.GetRequestDependencies()
   for (first, second, dep_reason) in depedencies:
     print '%s -> %s\t(%s)' % (first.request_id, second.request_id, dep_reason)