All graphs for this bug:
  https://chromeperf.appspot.com/group_report?bug_id=611040

Original alerts at time of bug-filing:
  https://chromeperf.appspot.com/group_report?keys=agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgICg9L3IvQoM


Bot(s) for this bug's original alert(s):

chromium-rel-win7-x64-dual

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


=== Bisection aborted ===
The bisect was aborted because The metric values for the initial "good" and "bad" revisions do not represent a clear regression.
Please contact the the team (see below) if you believe this is in error.

=== Warnings ===
The following warnings were raised by the bisect job:

 * Bisect failed to reproduce the regression with enough confidence.

===== TESTED REVISIONS =====
Revision         Mean     Std Dev   N   Good?
chromium@392581  3.46175  0.199149  18  good
chromium@392592  3.40112  0.139323  18  bad

Bisect job ran on: win_x64_perf_bisect
Bug ID: 611040

Test Command: src/tools/perf/run_benchmark -v --browser=release_x64 --output-format=chartjson --upload-results --also-run-disabled-tests memory.long_running_idle_gmail_background_tbmv2
Test Metric: Idle-v8-gc-scavenger_avg/Idle-v8-gc-scavenger_avg
Relative Change: 1.07%
Score: 0

Buildbot stdio: http://build.chromium.org/p/tryserver.chromium.perf/builders/win_x64_perf_bisect/builds/1223
Job details: https://chromeperf.appspot.com/buildbucket_job_status/9012931530712970768


Not what you expected? We'll investigate and get back to you!
  https://chromeperf.appspot.com/bad_bisect?try_job_id=5859733647392768

| 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 Tests>AutoBisect.  Thank you!

Kicked off another bisect here:
https://chromeperf.appspot.com/buildbucket_job_status/9012866553099034816

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


=== Bisection aborted ===
The bisect was aborted because The metric values for the initial "good" and "bad" revisions do not represent a clear regression.
Please contact the the team (see below) if you believe this is in error.

=== Warnings ===
The following warnings were raised by the bisect job:

 * Bisect failed to reproduce the regression with enough confidence.

===== TESTED REVISIONS =====
Revision         Mean     Std Dev   N   Good?
chromium@392581  3.42959  0.353894  18  good
chromium@392592  3.40275  0.174213  18  bad

Bisect job ran on: win_x64_perf_bisect
Bug ID: 611040

Test Command: src/tools/perf/run_benchmark -v --browser=release_x64 --output-format=chartjson --upload-results --also-run-disabled-tests memory.long_running_idle_gmail_background_tbmv2
Test Metric: Idle-v8-gc-scavenger_avg/Idle-v8-gc-scavenger_avg
Relative Change: 4.80%
Score: 0

Buildbot stdio: http://build.chromium.org/p/tryserver.chromium.perf/builders/win_x64_perf_bisect/builds/1226
Job details: https://chromeperf.appspot.com/buildbucket_job_status/9012866553099034816


Not what you expected? We'll investigate and get back to you!
  https://chromeperf.appspot.com/bad_bisect?try_job_id=5793789524836352

| 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 Tests>AutoBisect.  Thank you!

This regression occurred at the exact same time that the ref build was introduced. Is that a known pattern?

The bisect can't reproduce the change, so I'm marking WontFix.