message: decode strings to utf-8 and use universal_newlines for subprocess
  Cr-Commit-Position: refs/heads/main@{#35955}
diff: @@ -24,7 +24,10 @@ from tracing.value.diagnostics import reserved_infos
  def _GenerateOauthToken():
  args = ['luci-auth', 'token']
  - p = subprocess.Popen(args, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
  + p = subprocess.Popen(args,
  + universal_newlines=True,
  + stdout=subprocess.PIPE,
  + stderr=subprocess.PIPE)
  if p.wait() == 0:
  output = p.stdout.read()
  return output.strip()
  @@ -193,7 +196,7 @@ def _ApplyHacks(dicts):
  def _LoadHistogramSetFromProto(options):
  hs = histogram_set.HistogramSet()
  with options.input_results_file as f:
  - hs.ImportProto(f.read())
  + hs.ImportProto(f.read().decode('utf-8'))
  return hs
  