Started bisect job https://chromeperf.appspot.com/buildbucket_job_status/9004252051838642032

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

Hi alancutter@chromium.org, the bisect results pointed to your CL below as possibly
causing a regression. Please have a look at this info and see whether
your CL be related.


===== BISECT JOB RESULTS =====
Status: completed


===== SUSPECTED CL(s) =====
Subject : Avoid touching z-index in StyleAdjuster by using an isStackingContext flag instead
Author  : alancutter
Commit description:
  
This change moves logic in StyleAdjuster for changing the computed
z-index out into ComputedStyle::updateIsStackingContext().

This ensures we compute and inherit the correct z-index value
almost all of the time (see new test failure expectations).
Also by updating the flag outside of style resolution any new
CSS animations that affect stacking are now accounted for.

This patch is an alternative to https://codereview.chromium.org/2035793007.

BUG=616674, 375982

Review-Url: https://codereview.chromium.org/2047283002
Cr-Commit-Position: refs/heads/master@{#403844}
Commit  : a46d892723fe86a7f49113c46e3c40c2343724ce
Date    : Wed Jul 06 03:59:34 2016


===== TESTED REVISIONS =====
Revision         Mean    Std Dev      N  Good?
chromium@403836  989780  2.39996e-10  5  good
chromium@403840  989780  1.93053e-10  5  good
chromium@403842  989780  1.84069e-10  5  good
chromium@403843  989780  2.17793e-10  5  good
chromium@403844  993876  2.17793e-10  5  bad    <--

Bisect job ran on: win_x64_perf_bisect
Bug ID: 637835

Test Command: src/tools/perf/run_benchmark -v --browser=release_x64 --output-format=chartjson --upload-results --also-run-disabled-tests system_health.memory_desktop
Test Metric: load_games-memory:chrome:all_processes:reported_by_chrome:partition_alloc:effective_size_avg/load_games_lazors
Relative Change: 0.41%
Score: 99.9

Buildbot stdio: http://build.chromium.org/p/tryserver.chromium.perf/builders/win_x64_perf_bisect/builds/1402
Job details: https://chromeperf.appspot.com/buildbucket_job_status/9004252051838642032


Not what you expected? We'll investigate and get back to you!
  https://chromeperf.appspot.com/bad_bisect?try_job_id=5850038752772096

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|  X  | for more information addressing perf regression bugs. For feedback,
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Looking at the perf graphs for the bisected metric around that range I don't see a consistent regression around the commit date.
https://chromeperf.appspot.com/report?sid=a00fcfb63bb23e27f1a27ba2e4d147d398d4755e148cd9fc6726ce90333c004b&start_rev=402092&end_rev=405758