Refactor BenchmarkResult.Add to take enum for data_type

tools/perf/metrics/media.py

 # Copyright 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 import logging
 import os
 
 from metrics import Metric
+from telemetry.page import result_data_type
 
 class MediaMetric(Metric):
   """MediaMetric class injects and calls JS responsible for recording metrics.
 
   Default media metrics are collected for every media element in the page,
   such as decoded_frame_count, dropped_frame_count, decoded_video_bytes, and
   decoded_audio_bytes.
   """
   def __init__(self, tab):
     super(MediaMetric, self).__init__()
@@ skipping 27 matching lines @@
           ...
       }
     }
     """
     def AddOneResult(metric, unit):
       metrics = media_metric['metrics']
       for m in metrics:
         if m.startswith(metric):
           special_label = m[len(metric):]
           results.Add(trace + special_label, unit, str(metrics[m]),
-                      chart_name=metric, data_type='default')
+                      chart_name=metric,
+                      data_type=result_data_type.DEFAULT)
 
     trace = media_metric['id']
     if not trace:
       logging.error('Metrics ID is missing in results.')
       return
     AddOneResult('decoded_audio_bytes', 'bytes')
     AddOneResult('decoded_video_bytes', 'bytes')
     AddOneResult('decoded_frame_count', 'frames')
     AddOneResult('dropped_frame_count', 'frames')
     AddOneResult('playback_time', 'sec')
     AddOneResult('seek', 'sec')
     AddOneResult('time_to_play', 'sec')