telemetry: Add new metrics to smoothness benchmark.

tools/perf/metrics/smoothness_unittest.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 unittest
 import random
 
+from metrics import discrepancy
 from metrics import smoothness
 from metrics.gpu_rendering_stats import GpuRenderingStats
 from telemetry.page import page
 from telemetry.page.page_measurement_results import PageMeasurementResults
 from telemetry.core.backends.chrome.tracing_backend import RawTraceResultImpl
 from telemetry.core.backends.chrome.trace_result import TraceResult
 
 class MockTimer(object):
   """ An instance of this class is used as a global timer to generate
       random durations for stats and consistent timestamps for all mock trace
@@ skipping 214 matching lines @@
     smoothness.CalcResults(stats, res)
     res.DidMeasurePage()
 
     rs = rendering_stats
 
     # Scroll Results
     self.assertAlmostEquals(
         round(rs['totalTimeInSeconds'] / rs['numFramesSentToScreen'] * 1000.0,
               3),
         res.page_results[0]['mean_frame_time'].value, 2)
+    # We don't verify the correctness of the discrepancy computation
+    # itself, because we have a separate unit test for that purpose.
+    self.assertEquals(
+        round(discrepancy.FrameDiscrepancy(stats.screen_frame_timestamps,
+                                           True), 4),
+        res.page_results[0]['absolute_frame_discrepancy'].value)
+    self.assertEquals(
+        round(discrepancy.FrameDiscrepancy(stats.screen_frame_timestamps,
+                                           False), 4),
+        res.page_results[0]['relative_frame_discrepancy'].value)
     self.assertAlmostEquals(
         round(rs['droppedFrameCount'] / rs['numFramesSentToScreen'] * 100.0, 1),
         res.page_results[0]['dropped_percent'].value)
     self.assertAlmostEquals(
         round(rs['numImplThreadScrolls'] / (rs['numImplThreadScrolls'] +
                                             rs['numMainThreadScrolls']) * 100.0,
               1),
         res.page_results[0]['percent_impl_scrolled'].value)
     self.assertAlmostEquals(
         round(rs['numLayersDrawn'] / rs['numFramesSentToScreen'], 1),
@@ skipping 48 matching lines @@
     self.assertAlmostEquals(
         round(rs['totalTouchUILatency'] / rs['touchUICount'] * 1000.0, 3),
         res.page_results[0]['average_touch_ui_latency'].value)
     self.assertAlmostEquals(
         round(rs['totalTouchAckedLatency'] / rs['touchAckedCount'] * 1000.0, 3),
         res.page_results[0]['average_touch_acked_latency'].value)
     self.assertAlmostEquals(
         round(rs['totalScrollUpdateLatency'] / rs['scrollUpdateCount'] * 1000.0,
               3),
         res.page_results[0]['average_scroll_update_latency'].value)