Move smoothness to the new API

tools/perf/measurements/timeline_based_measurement.py

Index: tools/perf/measurements/timeline_based_measurement.py
diff --git a/tools/perf/measurements/timeline_based_measurement.py b/tools/perf/measurements/timeline_based_measurement.py
index a9e1ecc78bf3d3bc990d03c1e578ffec3b31ffc6..a726dc3b070fbc5002431c63b599f6e9cb0ac4bd 100644
--- a/tools/perf/measurements/timeline_based_measurement.py
+++ b/tools/perf/measurements/timeline_based_measurement.py
@@ -4,11 +4,11 @@
 
 from metrics import timeline as timeline_module
 from metrics import timeline_interaction_record as tir_module
+from metrics import smoothness
 from telemetry.page import page_measurement
 from telemetry.core.timeline import model as model_module
 
 
-
 # TimelineBasedMeasurement considers all instrumentation as producing a single
 # timeline. But, depending on the amount of instrumentation that is enabled,
 # overhead increases. The user of the measurement must therefore chose between
@@ -31,14 +31,14 @@ class _TimelineBasedMetrics(object):
 
   def FindTimelineInteractionRecords(self):
     # TODO(nduca): Add support for page-load interaction record.
-    return [tir_module.TimelineInteractionRecord(event) for
+    return [tir_module.TimelineInteractionRecord.FromEvent(event) for
             event in self._renderer_thread.IterAllAsyncSlices()
             if tir_module.IsTimelineInteractionRecord(event.name)]
 
   def CreateMetricsForTimelineInteractionRecord(self, interaction):
     res = []
     if interaction.is_smooth:
-      pass # TODO(nduca): res.append smoothness metric instance.
+      res.append(smoothness.SmoothnessMetric())
     return res
 
   def AddResults(self, results):