Add cleanup for measurements that use tracing

tools/perf/measurements/repaint.py

 # Copyright 2014 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 measurements import smoothness_controller
 from telemetry.page import page_measurement
 
 
 class Repaint(page_measurement.PageMeasurement):
   def __init__(self):
     super(Repaint, self).__init__('RunRepaint', False)
     self._smoothness_controller = None
 
   def WillRunActions(self, page, tab):
     tab.WaitForDocumentReadyStateToBeComplete()
     self._smoothness_controller = smoothness_controller.SmoothnessController()
     self._smoothness_controller.Start(page, tab)
     # Rasterize only what's visible.
     tab.ExecuteJavaScript(
         'chrome.gpuBenchmarking.setRasterizeOnlyVisibleContent();')
 
   def DidRunAction(self, page, tab, action):
     self._smoothness_controller.AddActionToIncludeInMetric(action)
 
   def DidRunActions(self, page, tab):
     self._smoothness_controller.Stop(tab)
 
   def MeasurePage(self, page, tab, results):
     self._smoothness_controller.AddResults(tab, results)
+
+  def CleanUpAfterPage(self, _, tab):
+    self._smoothness_controller.CleanUp(tab)