message: Write PluginData.content as bytes explicitly
diff: @@ -46,7 +46,6 @@ from tensorflow.python.util import deprecation
  from tensorflow.python.util import tf_contextlib
  from tensorflow.python.util.tf_export import tf_export
  -
  # A global dictionary mapping graph keys to a list of summary writer init ops.
  _SUMMARY_WRITER_INIT_OP = {}
  @@ -756,7 +755,7 @@ def run_metadata(name, data, step):
  # the rationale.
  summary_metadata.plugin_data.plugin_name = "graph_run_metadata"
  # version number = 1
  - summary_metadata.plugin_data.content = "1"
  + summary_metadata.plugin_data.content = b"1"
  with summary_scope(name,
  "graph_run_metadata_summary",
  @@ -787,7 +786,7 @@ def run_metadata_graphs(name, data, step):
  # the rationale.
  summary_metadata.plugin_data.plugin_name = "graph_run_metadata_graph"
  # version number = 1
  - summary_metadata.plugin_data.content = "1"
  + summary_metadata.plugin_data.content = b"1"
  data = config_pb2.RunMetadata(
  function_graphs=data.function_graphs,
  @@ -825,7 +824,7 @@ def keras_model(name, data, step):
  # the rationale.
  summary_metadata.plugin_data.plugin_name = "graph_keras_model"
  # version number = 1
  - summary_metadata.plugin_data.content = "1"
  + summary_metadata.plugin_data.content = b"1"
  json_string = data.to_json()
  