[benchmarking] remove ref build related logics on sharding

Reference build has been disabled everywhere on perf waterfall. This CL removes the footprints of it in the sharding logic.

Bug: chromium:1130157
Change-Id: If64f8435f705710305a0c6fe24610ceac7cf6275
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2451514
Auto-Submit: Wenbin Zhang <wenbinzhang@google.com>
Reviewed-by: John Chen <johnchen@chromium.org>
Commit-Queue: John Chen <johnchen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#814359}

tools/perf/core/sharding_map_generator.py

@@ -87,8 +87,7 @@ def generate_sharding_map(benchmarks_to_shard, timing_data, num_shards, debug):
                                  benchmark_name_to_config)
       else:
         break
-    # Double time_per_shard to account for reference benchmark run.
-    debug_map[shard_name]['expected_total_time'] = time_per_shard * 2
+    debug_map[shard_name]['expected_total_time'] = time_per_shard
     if time_per_shard > max_shard_time:
       max_shard_time = time_per_shard
       max_shard_index = i
@@ -96,16 +95,15 @@ def generate_sharding_map(benchmarks_to_shard, timing_data, num_shards, debug):
       min_shard_time = time_per_shard
       min_shard_index = i
 
-    predicted_shard_timings.append((shard_name, time_per_shard * 2))
+    predicted_shard_timings.append((shard_name, time_per_shard))
 
   sharding_map['extra_infos'] = collections.OrderedDict([
       ('num_stories', num_stories),
-      # Double all the time stats by 2 to account for reference build.
-      ('predicted_min_shard_time', min_shard_time * 2),
+      ('predicted_min_shard_time', min_shard_time),
       ('predicted_min_shard_index', min_shard_index),
-      ('predicted_max_shard_time', max_shard_time * 2),
+      ('predicted_max_shard_time', max_shard_time),
       ('predicted_max_shard_index', max_shard_index),
-      ])
+  ])
 
   if debug:
     sharding_map['extra_infos'].update(debug_map)

tools/perf/generate_perf_sharding.py

@@ -116,13 +116,6 @@ def _LoadTimingData(args):
   builder, timing_file_path = args
   data = retrieve_story_timing.FetchAverageStoryTimingData(
       configurations=[builder.name], num_last_days=5)
-  # Running against a reference build doubles our runtime.
-  # Double the expected duration of each story to account
-  # for this. Note that gtest perf tests can't run against
-  # reference builds, so this does not apply to them.
-  if builder.run_reference_build:
-    for story in data:
-      story['duration'] = unicode(float(story['duration']) * 2.0)
   for executable in builder.executables:
     data.append({unicode('duration'): unicode(
                     float(executable.estimated_runtime)),