All graphs for this bug:
  https://chromeperf.appspot.com/group_report?bug_id=768381

(For debugging:) Original alerts at time of bug-filing:
  https://chromeperf.appspot.com/group_report?sid=79b3084454fe79e2ebea1b443402dc9a30be563fb1d66c7ea146cc0f1aef2284


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

chromium-rel-win8-dual

Started bisect job https://chromeperf.appspot.com/buildbucket_job_status/8967471733269478656

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

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


=== BISECT JOB RESULTS ===
Perf regression found with culprit

Suspected Commit
  Author : Eric Seckler
  Commit : 1b697fc546af51e355c458bc4e10f821a1c8d551
  Date   : Sun Sep 24 07:41:53 2017
  Subject: [viz] Ensure that ClientLTFS acknowledges racy BeginFrames.

Bisect Details
  Configuration: win_8_perf_bisect
  Benchmark    : media.tough_video_cases
  Metric       : dropped_frame_count/video.html?src_crowd1080.mp4
  Change       : 1400.00% | 0.111111111111 -> 2.11111111111

Revision             Result                    N
chromium@503949      0.111111 +- 0.942809      9      good
chromium@503951      0.333333 +- 1.41421       9      good
chromium@503952      2.11111 +- 3.29983        9      bad       <--

To Run This Test
  src/tools/perf/run_benchmark -v --browser=release --output-format=chartjson --upload-results --pageset-repeat=1 --also-run-disabled-tests --story-filter=video.html.src.crowd1080.mp4 media.tough_video_cases

More information on addressing performance regressions:
  http://g.co/ChromePerformanceRegressions

Debug information about this bisect:
  https://chromeperf.appspot.com/buildbucket_job_status/8967471733269478656


For feedback, file a bug with component Speed>Bisection

 Issue 768432  has been merged into this issue.

 Issue 768547  has been merged into this issue.

 Issue 768537  has been merged into this issue.

 Issue 768750  has been merged into this issue.

 Issue 768861  has been merged into this issue.

I found the likely cause of this - I forgot to set needs_begin_frames_ in CLTFS. Fix is out in https://crrev.com/c/686494.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/50b050167d6fd83aca749c8e04e993c73554cfc3

commit 50b050167d6fd83aca749c8e04e993c73554cfc3
Author: Eric Seckler <eseckler@chromium.org>
Date: Wed Sep 27 12:34:22 2017

[viz] Set needs_begin_frames_ in CLTFS

Bug:  768381 
Change-Id: I22caaeb74d37deebfda7118b7271739b27f74fa3
Reviewed-on: https://chromium-review.googlesource.com/686494
Reviewed-by: Fady Samuel <fsamuel@chromium.org>
Commit-Queue: Eric Seckler <eseckler@chromium.org>
Cr-Commit-Position: refs/heads/master@{#504637}
[modify] https://crrev.com/50b050167d6fd83aca749c8e04e993c73554cfc3/components/viz/client/client_layer_tree_frame_sink.cc

Graphs seem to have returned to pre-regression levels.