cc: Remove unused metrics from RenderingStats.

tools/perf/metrics/smoothness.py

Index: tools/perf/metrics/smoothness.py
diff --git a/tools/perf/metrics/smoothness.py b/tools/perf/metrics/smoothness.py
index ed89f8b1af662848e8904d06685084ea8ea9501c..ef4bf05e354923c05ccd1d83d7a8167202fdfac9 100644
--- a/tools/perf/metrics/smoothness.py
+++ b/tools/perf/metrics/smoothness.py
@@ -171,20 +171,20 @@ def CalcResults(benchmark_stats, results):
   s = benchmark_stats
 
   frame_times = []
-  for i in xrange(1, len(s.screen_frame_timestamps)):
+  for i in xrange(1, len(s.frame_timestamps)):
     frame_times.append(
-        round(s.screen_frame_timestamps[i] - s.screen_frame_timestamps[i-1], 2))
+        round(s.frame_timestamps[i] - s.frame_timestamps[i-1], 2))
 
   # List of raw frame times.
   results.Add('frame_times', 'ms', frame_times)
 
   # Arithmetic mean of frame times. Not the generalized mean.
   results.Add('mean_frame_time', 'ms',
-              Average(s.total_time, s.screen_frame_count, 1000, 3))
+              Average(s.total_time, len(s.frame_timestamps), 1000, 3))
 
   # Absolute discrepancy of frame time stamps.
   results.Add('jank', '',
-              round(discrepancy.FrameDiscrepancy(s.screen_frame_timestamps,
+              round(discrepancy.FrameDiscrepancy(s.frame_timestamps,
                                                  True), 4))
 
   # Are we hitting 60 fps for 95 percent of all frames? (Boolean value)
@@ -209,4 +209,3 @@ def FindTimelineMarker(timeline, name):
   if len(events) != 1:
     raise MissingTimelineMarker(name)
   return events[0]
-