telemetry: Add tough scheduling cases

tools/perf/measurements/smoothness.py

 # Copyright (c) 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 smoothness
 from metrics import timeline
 from telemetry.page import page_test
 from telemetry.page import page_measurement
 
 
@@ skipping 41 matching lines @@
     self._metric.Stop(page, tab)
 
   def MeasurePage(self, page, tab, results):
     self._metric.AddResults(tab, results)
 
     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)
+
+class SmoothnessWithRestart(Smoothness):
+  def NeedsBrowserRestartAfterEachRun(self, browser):
+    return True