logs:
https://luci-logdog.appspot.com/v/?s=chrome%2Fbb%2Fchromium.perf%2FAndroid_Nexus5X_Perf__3_%2F3705%2F%2B%2Frecipes%2Fsteps%2Fv8.key_mobile_sites_smooth%2F0%2Fstdout

Traceback (most recent call last):
  RunBenchmark at /b/c/b/Android_Nexus5X_Perf__3_/src/third_party/catapult/telemetry/telemetry/internal/story_runner.py:359
    benchmark.ShouldTearDownStateAfterEachStorySetRun())
  Run at /b/c/b/Android_Nexus5X_Perf__3_/src/third_party/catapult/telemetry/telemetry/internal/story_runner.py:237
    _RunStoryAndProcessErrorIfNeeded(story, results, state, test)
  _RunStoryAndProcessErrorIfNeeded at /b/c/b/Android_Nexus5X_Perf__3_/src/third_party/catapult/telemetry/telemetry/internal/story_runner.py:88
    state.RunStory(results)
  traced_function at /b/c/b/Android_Nexus5X_Perf__3_/src/third_party/catapult/common/py_trace_event/py_trace_event/trace_event_impl/decorators.py:52
    return func(*args, **kwargs)
  RunStory at /b/c/b/Android_Nexus5X_Perf__3_/src/third_party/catapult/telemetry/telemetry/page/shared_page_state.py:302
    self._current_page, self._current_tab, results)
  traced_function at /b/c/b/Android_Nexus5X_Perf__3_/src/third_party/catapult/common/py_trace_event/py_trace_event/trace_event_impl/decorators.py:75
    return func(*args, **kwargs)
  ValidateAndMeasurePage at /b/c/b/Android_Nexus5X_Perf__3_/src/tools/perf/measurements/v8_gc_times.py:40
    self._AddV8MetricsToResults(renderer_process, results)
  traced_function at /b/c/b/Android_Nexus5X_Perf__3_/src/third_party/catapult/common/py_trace_event/py_trace_event/trace_event_impl/decorators.py:52
    return func(*args, **kwargs)
  _AddV8MetricsToResults at /b/c/b/Android_Nexus5X_Perf__3_/src/tools/perf/measurements/v8_gc_times.py:55
    self._AddCpuTimeStatsToResults(thread, results)
  traced_function at /b/c/b/Android_Nexus5X_Perf__3_/src/third_party/catapult/common/py_trace_event/py_trace_event/trace_event_impl/decorators.py:52
    return func(*args, **kwargs)
  _AddCpuTimeStatsToResults at /b/c/b/Android_Nexus5X_Perf__3_/src/tools/perf/measurements/v8_gc_times.py:195
    cpu_time = sum(s.thread_duration for s in thread.toplevel_slices)
TypeError: unsupported operand type(s) for +: 'float' and 'NoneType'

Started bisect job https://chromeperf.appspot.com/buildbucket_job_status/8981218510564806528

Started bisect job https://chromeperf.appspot.com/buildbucket_job_status/8981218482526706208

Started bisect job https://chromeperf.appspot.com/buildbucket_job_status/8981218432550381104

=== BISECT JOB RESULTS ===
NO Test failure found

Bisect Details
  Configuration: android_nexus5X_perf_bisect
  Benchmark    : v8.key_mobile_sites_smooth
  Metric       : duration/http___www.theverge.com_2012_10_28_3568746_amazon-7-inch-fire-hd-ipad-mini-ad-ballsy

Revision             Exit Code      N
chromium@465924      0 +- N/A       20      good
chromium@465972      0 +- N/A       20      bad

To Run This Test
  src/tools/perf/run_benchmark -v --browser=android-chromium --output-format=chartjson --upload-results --pageset-repeat=1 --also-run-disabled-tests --story-filter=http...iphone.capitolvolkswagen.com.index.htm.new.inventory.p.2Fsb.new.p.2Ehtm.p.3Freset.p.3DInventoryListing v8.key_mobile_sites_smooth

Debug Info
  https://chromeperf.appspot.com/buildbucket_job_status/8981218510564806528

Is this bisect wrong?
  https://chromeperf.appspot.com/bad_bisect?try_job_id=6184339018088448


| O O | Visit http://www.chromium.org/developers/speed-infra/perf-bug-faq
|  X  | for more information addressing perf regression bugs. For feedback,
| / \ | file a bug with component Speed>Bisection.  Thank you!

=== Auto-CCing suspected CL author nhiroki@chromium.org ===

Hi nhiroki@chromium.org, the bisect results pointed to your CL, please take a look at the
results.


=== BISECT JOB RESULTS ===
Test failure found with culprit

Suspected Commit
  Author : nhiroki
  Commit : 7800a474d39eacc36c6c247f6a956e15f5d2489a
  Date   : Thu Apr 20 10:06:51 2017
  Subject: Reland of Worker: Introduce per-global-scope task scheduler

Bisect Details
  Configuration: android_nexus6_perf_bisect
  Benchmark    : v8.key_mobile_sites_smooth
  Metric       : duration/http___www.theverge.com_2012_10_28_3568746_amazon-7-inch-fire-hd-ipad-mini-ad-ballsy

Revision             Exit Code      N
chromium@465942      0 +- N/A       20      good
chromium@465955      0 +- N/A       20      good
chromium@465961      0 +- N/A       20      good
chromium@465962      1 +- N/A       20      bad       <--
chromium@465963      1 +- N/A       20      bad
chromium@465964      1 +- N/A       20      bad
chromium@465967      1 +- N/A       20      bad

To Run This Test
  src/tools/perf/run_benchmark -v --browser=android-chromium --output-format=chartjson --upload-results --pageset-repeat=1 --also-run-disabled-tests --story-filter=http...www.theverge.com.2012.10.28.3568746.amazon.7.inch.fire.hd.ipad.mini.ad.ballsy v8.key_mobile_sites_smooth

Debug Info
  https://chromeperf.appspot.com/buildbucket_job_status/8981218432550381104

Is this bisect wrong?
  https://chromeperf.appspot.com/bad_bisect?try_job_id=6340806824165376


| O O | Visit http://www.chromium.org/developers/speed-infra/perf-bug-faq
|  X  | for more information addressing perf regression bugs. For feedback,
| / \ | file a bug with component Speed>Bisection.  Thank you!

=== BISECT JOB RESULTS ===
NO Test failure found

Bisect Details
  Configuration: android_nexus5_perf_bisect
  Benchmark    : v8.key_mobile_sites_smooth
  Metric       : duration/http___www.theverge.com_2012_10_28_3568746_amazon-7-inch-fire-hd-ipad-mini-ad-ballsy

Revision             Exit Code      N
chromium@465934      1 +- N/A       20      good
chromium@465963      1 +- N/A       20      bad

To Run This Test
  src/tools/perf/run_benchmark -v --browser=android-chromium --output-format=chartjson --upload-results --pageset-repeat=1 --also-run-disabled-tests v8.key_mobile_sites_smooth

Debug Info
  https://chromeperf.appspot.com/buildbucket_job_status/8981218482526706208

Is this bisect wrong?
  https://chromeperf.appspot.com/bad_bisect?try_job_id=5312185510658048


| O O | Visit http://www.chromium.org/developers/speed-infra/perf-bug-faq
|  X  | for more information addressing perf regression bugs. For feedback,
| / \ | file a bug with component Speed>Bisection.  Thank you!