[telemetry] Enable Chrome logging in TracingBackendTest

telemetry/telemetry/internal/backends/chrome_inspector/tracing_backend_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.
 
 from functools import wraps
 import logging
 import sys
 import timeit
 import unittest
 
@@ skipping 29 matching lines @@
   return WrappedTest
 
 
 class TracingBackendTest(tab_test_case.TabTestCase):
 
   # Number of consecutively requested memory dumps.
   _REQUESTED_DUMP_COUNT = 3
 
   @classmethod
   def CustomizeBrowserOptions(cls, options):
+    options.enable_logging = True
     options.AppendExtraBrowserArgs([
         # Memory maps currently cannot be retrieved on sandboxed processes.
         # See crbug.com/461788.
         '--no-sandbox',
 
         # Workaround to disable periodic memory dumps. See crbug.com/513692.
         '--enable-memory-benchmarking'
     ])
 
   def setUp(self):
@@ skipping 186 matching lines @@
     n1 = 1000
     while True:
       t1 = self._MeasureReadTime(n1)
       if t1 > 0.01:
         break
       n1 *= 5
     t2 = self._MeasureReadTime(n1 * 10)
     # Time is an illusion, CPU time is doubly so, allow great deal of tolerance.
     toleranceFactor = 5
     self.assertLess(t2, t1 * 10 * toleranceFactor)