Update run_performance_tests.py to use '--story-shard-begin-index' and...

Update run_performance_tests.py to use '--story-shard-begin-index' and '--story-shard-end-index' flags

Bug:866095
Change-Id: I92c07d23a98910fa0840811fe45f2daa8b2ba8a1

TBR=perezju@chromium.org, eyaich@chromium.org

# Bypass unrelated PRESUBMIT lint error

No-Presubmit: true
Change-Id: I92c07d23a98910fa0840811fe45f2daa8b2ba8a1
Reviewed-on: https://chromium-review.googlesource.com/1150420
Commit-Queue: Ned Nguyen <nednguyen@google.com>
Reviewed-by: Ned Nguyen <nednguyen@google.com>
Cr-Commit-Position: refs/heads/master@{#577990}

testing/scripts/run_performance_tests.py

@@ -119,10 +119,10 @@ def execute_benchmark(benchmark, isolated_out_dir,
   if stories:
     if 'begin' in stories.keys():
       per_benchmark_args.append(
-          ('--experimental-story-shard-begin-index=%d' % stories['begin']))
+          ('--story-shard-begin-index=%d' % stories['begin']))
     if 'end' in stories.keys():
       per_benchmark_args.append(
-          ('--experimental-story-shard-end-index=%d' % stories['end']))
+          ('--story-shard-end-index=%d' % stories['end']))
 
   # We don't care exactly what these are. In particular, the perf results
   # could be any format (chartjson, legacy, histogram). We just pass these