All graphs for this bug:
  https://chromeperf.appspot.com/group_report?bug_id=628290

Original alerts at time of bug-filing:
  https://chromeperf.appspot.com/group_report?keys=agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgICgipzLoQoM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgICg8qu3swkM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgICgis7B5gkM


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

chromium-rel-win7-single
chromium-rel-win8-dual

Started bisect job https://chromeperf.appspot.com/buildbucket_job_status/9007143261762369328

===== 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@404580  71058074  317086   12  good
chromium@404721  71063770  372346   12  bad

Bisect job ran on: win_8_perf_bisect
Bug ID: 628290

Test Command: src/tools/perf/run_benchmark -v --browser=release --output-format=chartjson --upload-results --also-run-disabled-tests system_health.memory_desktop
Test Metric: load_media-memory:chrome:all_processes:reported_by_chrome:winheap:effective_size_avg/load_media_soundcloud
Relative Change: 0.08%
Score: 0

Buildbot stdio: http://build.chromium.org/p/tryserver.chromium.perf/builders/win_8_perf_bisect/builds/2036
Job details: https://chromeperf.appspot.com/buildbucket_job_status/9007143261762369328


Not what you expected? We'll investigate and get back to you!
  https://chromeperf.appspot.com/bad_bisect?try_job_id=5846959068282880

| 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!

 Issue 628289  has been merged into this issue.

Started bisect job https://chromeperf.appspot.com/buildbucket_job_status/9007065203537954048

Started bisect job https://chromeperf.appspot.com/buildbucket_job_status/9007065080949099120

Another bisect on a different chart: https://build.chromium.org/p/tryserver.chromium.perf/builders/win_perf_bisect/builds/6701

===== 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@404580  66995868  1386486  12  good
chromium@404721  67563520  1672949  12  bad

Bisect job ran on: win_perf_bisect
Bug ID: 628290

Test Command: src/tools/perf/run_benchmark -v --browser=release --output-format=chartjson --upload-results --also-run-disabled-tests system_health.memory_desktop
Test Metric: load_tools-memory:chrome:all_processes:reported_by_chrome:v8:effective_size_avg/load_tools_docs
Relative Change: 1.73%
Score: 0

Buildbot stdio: http://build.chromium.org/p/tryserver.chromium.perf/builders/win_perf_bisect/builds/6701
Job details: https://chromeperf.appspot.com/buildbucket_job_status/9007065080949099120


Not what you expected? We'll investigate and get back to you!
  https://chromeperf.appspot.com/bad_bisect?try_job_id=5842286328414208

| 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!

The bisect can't reproduce this on multiple charts. Furthermore, the regression (r404580→r404721) came after a symmetrical improvement (r402562→r402704). Therefore, I'm going to assume this was due to some infrastructure change and mark this as WontFix.