Update fieldtrial_util To Handle Combined Fieldtrial Config Format

tools/variations/fieldtrial_to_struct.py

 #!/usr/bin/env python
 # Copyright 2015 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.
 
 import itertools
 import json
 import os.path
 import sys
 import optparse
@@ skipping 56 matching lines @@
 
 def _GenerateTrials(config, platform):
   for study_name in sorted(config.keys()):
     study = _CreateTrial(study_name, config[study_name], platform)
     # To avoid converting studies with empty experiments (e.g. the study doesn't
     # apply to the target platform), this generator only yields studies that
     # have non-empty experiments.
     if study['experiments']:
       yield study
 
+def ConfigToStudies(config, platform):
+  """Returns the applicable studies from config for the platform."""
+  return [study for study in _GenerateTrials(config, platform)]
+
 def _FieldTrialConfigToDescription(config, platform):
   return {
     'elements': {
       'kFieldTrialConfig': {
-        'studies': [study for study in _GenerateTrials(config, platform)]
+        'studies': ConfigToStudies(config, platform)
       }
     }
   }
 
 def main(arguments):
   parser = optparse.OptionParser(
       description='Generates a struct from a JSON description.',
       usage='usage: %prog [option] -s schema -p platform description')
   parser.add_option('-b', '--destbase',
       help='base directory of generated files.')
@@ skipping 36 matching lines @@
 
   schema = _Load(opts.schema)
   description = _LoadFieldTrialConfig(description_filename, opts.platform)
   json_to_struct.GenerateStruct(
       basepath, output_root, opts.namespace, schema, description,
       os.path.split(description_filename)[1], os.path.split(opts.schema)[1],
       opts.year)
 
 if __name__ == '__main__':
   main(sys.argv[1:])