message: Use binary mode for proto ingestion
  Cr-Commit-Position: refs/heads/main@{#35960}
diff: @@ -195,8 +195,8 @@ def _ApplyHacks(dicts):
  def _LoadHistogramSetFromProto(options):
  hs = histogram_set.HistogramSet()
  - with options.input_results_file as f:
  - hs.ImportProto(f.read().decode('utf-8'))
  + with open(options.input_results_file, 'rb') as f:
  + hs.ImportProto(f.read())
  return hs
  