Remove usage of bot_utils.GetDeviceAffinity in perf_data_generator

tools/perf/core/perf_data_generator.py

 #!/usr/bin/env 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.
 
 # pylint: disable=too-many-lines
 
 """Script to generate chromium.perf.json and chromium.perf.fyi.json in
 the src/testing/buildbot directory and benchmark.csv in the src/tools/perf
 directory. Maintaining these files by hand is too unwieldy.
@@ skipping 623 matching lines @@
   num_shards = len(tester_config['swarming_dimensions'][0]['device_ids'])
   current_shard = 0
   for benchmark in benchmarks:
     if not ShouldBenchmarkBeScheduled(benchmark, tester_config['platform']):
       continue
 
     # First figure out swarming dimensions this test needs to be triggered on.
     # For each set of dimensions it is only triggered on one of the devices
     swarming_dimensions = []
     for dimension in tester_config['swarming_dimensions']:
-      device_affinity = None
-      if benchmark_sharding_map:
-        sharding_map = benchmark_sharding_map.get(str(num_shards), None)
-        if not sharding_map:
-          raise Exception('Invalid number of shards, generate new sharding map')
-        device_affinity = sharding_map.get(benchmark.Name(), None)
-      else:
-        # No sharding map was provided, default to legacy device
-        # affinity algorithm
-        device_affinity = bot_utils.GetDeviceAffinity(
-          num_shards, benchmark.Name())
+      sharding_map = benchmark_sharding_map.get(str(num_shards), None)
+      if not sharding_map:
+        raise Exception('Invalid number of shards, generate new sharding map')
+      device_affinity = sharding_map.get(benchmark.Name(), None)
       if device_affinity is None:
         raise Exception('Device affinity for benchmark %s not found'
           % benchmark.Name())
       swarming_dimensions.append(
           get_swarming_dimension(dimension, device_affinity))
 
     test = generate_telemetry_test(
       swarming_dimensions, benchmark.Name(), browser_name)
     isolated_scripts.append(test)
     # Now create another executable for this benchmark on the reference browser
@@ skipping 337 matching lines @@
       return 0
     else:
       print ('The perf JSON config files are not up-to-date. Please run %s '
              'without --validate-only flag to update the perf JSON '
              'configs and benchmark.csv.') % sys.argv[0]
       return 1
   else:
     update_all_tests([fyi_waterfall, waterfall])
     update_benchmark_csv()
   return 0