telemetry: Add unit 'score' to 'mostly_smooth' metric.

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.
 
 from metrics import Metric
 from metrics import rendering_stats
 from metrics import statistics
 from telemetry.page import page_measurement
 
 TIMELINE_MARKER = 'Smoothness'
@@ skipping 61 matching lines @@
                                                 len(self._stats.frame_times))
     results.Add('mean_frame_time', 'ms', round(mean_frame_time, 3))
 
     # Absolute discrepancy of frame time stamps.
     jank = statistics.FrameDiscrepancy(self._stats.frame_timestamps)
     results.Add('jank', '', round(jank, 4))
 
     # Are we hitting 60 fps for 95 percent of all frames?
     # We use 19ms as a somewhat looser threshold, instead of 1000.0/60.0.
     percentile_95 = statistics.Percentile(self._stats.frame_times, 95.0)
-    results.Add('mostly_smooth', '', 1.0 if percentile_95 < 19.0 else 0.0)
+    results.Add('mostly_smooth', 'score', 1.0 if percentile_95 < 19.0 else 0.0)

[fmeawad, 2014/01/03 19:39:47]

Would '%' also work? is it a percentile?

[ernstm, 2014/01/04 01:08:47]

It is a binary value (0 or 1), so score seemed the best option from what we
already have in unit-info.json. Another reason why percent would not work is
that it is reported as 'lower is better'.

 
     if tab.browser.platform.IsRawDisplayFrameRateSupported():
       for r in tab.browser.platform.GetRawDisplayFrameRateMeasurements():
         if r.value is None:
           raise MissingDisplayFrameRateError(r.name)
         results.Add(r.name, r.unit, r.value)