predictors: Move the configuration of speculative prefetch to field trials.

tools/resource_prefetch_predictor/generate_test_data.py

 #!/usr/bin/python
 #
 # 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.
 
 """Loads a set of web pages several times on a device, and extracts the
 predictor database.
 Also generates a WPR archive for another page.
 """
@@ skipping 15 matching lines @@
 
 sys.path.append(os.path.join(_SRC_PATH, 'tools', 'android', 'loading'))
 import device_setup
 from options import OPTIONS
 import page_track
 
 import prefetch_predictor_common
 
 
 _PAGE_LOAD_TIMEOUT = 40
+_LEARNING_FLAGS = [
+    '--force-fieldtrials=trial/group',
+    '--force-fieldtrial-params=trial.group:mode/learning',
+    '--enable-features="SpeculativeResourcePrefetching<trial"']
 
 
 def _CreateArgumentParser():
   """Creates and returns the argument parser."""
   parser = argparse.ArgumentParser(
       ('Loads a set of web pages several times on a device, and extracts the '
        'predictor database.'), parents=[OPTIONS.GetParentParser()])
   parser.add_argument('--device', help='Device ID')
   parser.add_argument('--urls_filename', help='File containing a list of URLs '
                       '(one per line). URLs can be repeated.')
@@ skipping 45 matching lines @@
 
   parser = _CreateArgumentParser()
   args = parser.parse_args()
   OPTIONS.SetParsedArgs(args)
 
   device = prefetch_predictor_common.FindDevice(args.device)
   if device is None:
     logging.error('Could not find device: %s.', args.device)
     sys.exit(1)
 
-  chrome_controller = prefetch_predictor_common.Setup(
-      device, ['--speculative-resource-prefetching=learning'])
+  chrome_controller = prefetch_predictor_common.Setup(device, _LEARNING_FLAGS)
   _GenerateDatabase(chrome_controller, args.urls_filename,
                     args.output_filename, int(args.url_repeat))
   _GenerateWprArchive(device, args.test_url, args.wpr_archive)
 
 
 if __name__ == '__main__':
   main()