cc: Add best_record_time to rendering stats.

tools/perf/metrics/smoothness.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 os
 import math
 
 from telemetry.core import util
 from metrics import discrepancy
 
 TIMELINE_MARKER = 'smoothness_scroll'
@@ skipping 69 matching lines @@
   return total
 
 def Average(numerator, denominator, scale = None, precision = None):
   numerator_total = Total(numerator)
   denominator_total = Total(denominator)
   if denominator_total == 0:
     return 0
   avg = numerator_total / denominator_total
   if scale:
     avg *= scale
-  if precision:
+  if precision == None:
+    pass
+  elif precision == 0:
+    avg = int(avg)
+  else:
     avg = round(avg, precision)
   return avg
 
 def DivideIfPossibleOrZero(numerator, denominator):
   if not denominator:
     return 0.0
   else:
     return numerator / denominator
 
 def GeneralizedMean(values, exponent):
@@ skipping 67 matching lines @@
   results.Add('mean_frame_time', 'ms',
               Average(s.total_time, s.screen_frame_count, 1000, 3))
   # Absolute discrepancy of frame time stamps.
   results.Add('jank', '',
               round(discrepancy.FrameDiscrepancy(s.screen_frame_timestamps,
                                                  True), 4))
   # Are we hitting 60 fps for 95 percent of all frames?
   # We use 17ms as a slightly looser threshold, instead of 1000.0/60.0.
   results.Add('mostly_smooth', '',
               Percentile(frame_times, 95.0) < 17.0)