No need to cast to str in media metric results.

BUG=291379

Review URL: https://chromiumcodereview.appspot.com/24159003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@223501 0039d316-1c4b-4281-b951-d872f2087c98

tools/perf/metrics/media.py

@@ -56,7 +56,7 @@ class MediaMetric(Metric):
       for m in metrics:
         if m.startswith(metric):
           special_label = m[len(metric):]
-          results.Add(trace + special_label, unit, str(metrics[m]),
+          results.Add(trace + special_label, unit, metrics[m],
                       chart_name=metric, data_type='default')
 
     trace = media_metric['id']