All graphs for this bug:
  https://chromeperf.appspot.com/group_report?bug_id=602763

Original alerts at time of bug-filing:
  https://chromeperf.appspot.com/group_report?keys=agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgICg2OqLsgsM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgICguNOftgkM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgICg2PezuwoM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgICguOD8rQkM


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

chromium-rel-mac-hdd
chromium-rel-mac11

The bisect is still in progress, but this change looks very likely:

commit	5a3c87b37a46ce1b0813f0530d981165daaa7cfe	
author	ccameron <ccameron@chromium.org>	Sun Apr 10 05:34:35 2016
committer	Commit bot <commit-bot@chromium.org>	Sun Apr 10 05:36:23 2016
Mac: Clean up ImageTransportSurfaceOverlayMac timing

This patch substantially improves smoothness of GPU-bound applications, and appears to have no effect on non-GPU-bound applications.

Bisect re-kicked with wider revision range as the previous bisect failed.

Details on the below link:
=========================
https://chromeperf.appspot.com/group_report?bug_id=602763

Thank you!

Note, the graphs for chromium-rel-mac-hdd may not be very helpful because the increase happens after a ~3 day period of no results (maybe the machines may have been changed/restarted during that time, affected the results? Or maybe there was a regression there, although the regression range is relatively large).

===== 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@384356  33.3827  10.3782  18  good
chromium@387000  29.5788  8.73456  18  bad

Bisect job ran on: android_webview_aosp_perf_bisect
Bug ID: 602763

Test Command: src/tools/perf/run_benchmark -v --browser=android-chromium --output-format=chartjson --upload-results --also-run-disabled-tests smoothness.gpu_rasterization.tough_path_rendering_cases
Test Metric: percentage_smooth/percentage_smooth
Relative Change: 15.37%
Score: 0

Buildbot stdio: http://build.chromium.org/p/tryserver.chromium.perf/builders/android_webview_aosp_perf_bisect/builds/123
Job details: https://chromeperf.appspot.com/buildbucket_job_status/9014084399714381744


Not what you expected? We'll investigate and get back to you!
  https://chromeperf.appspot.com/bad_bisect?try_job_id=5831981514883072

| 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!

Re-kicked another bisect as the previous bisect did not produce any suspects.
https://chromeperf.appspot.com/buildbucket_job_status/9013498793066133792

Started a bisect on android-webview for microsoft.com.
https://chromeperf.appspot.com/buildbucket_job_status/9013029345405000768

This recovered with ericrk's r397738