Enable the tracingMetric on the system_health.common benchmarks

tools/perf/benchmarks/system_health.py

 # Copyright 2016 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 re
 
 from benchmarks import page_cycler_v2
 
 from core import perf_benchmark
 
@@ skipping 21 matching lines @@
 
   https://goo.gl/Jek2NL.
   """
 
   def CreateTimelineBasedMeasurementOptions(self):
     options = timeline_based_measurement.Options(
         chrome_trace_category_filter.ChromeTraceCategoryFilter())
     options.config.chrome_trace_config.category_filter.AddFilterString('rail')
     options.config.enable_battor_trace = True
     options.config.enable_chrome_trace = True
-    options.SetTimelineBasedMetrics(['clockSyncLatencyMetric', 'powerMetric'])
+    options.SetTimelineBasedMetrics([
+        'clockSyncLatencyMetric',
+        'powerMetric',
+        'tracingMetric'
+    ])
     page_cycler_v2.AugmentOptionsForLoadingMetrics(options)
     return options
 
   def CreateStorySet(self, options):
     return page_sets.SystemHealthStorySet(platform=self.PLATFORM)
 
   @classmethod
   def ShouldTearDownStateAfterEachStoryRun(cls):
     return True
 
@@ skipping 119 matching lines @@
   and load a blank page with multiprocess enabled.
   """
 
   def SetExtraBrowserOptions(self, options):
     options.AppendExtraBrowserArgs(
         ['--webview-sandboxed-renderer'])
 
   @classmethod
   def Name(cls):
     return 'system_health.webview_startup_multiprocess'