All graphs for this bug:
  https://chromeperf.appspot.com/group_report?bug_id=883847

(For debugging:) Original alerts at time of bug-filing:
  https://chromeperf.appspot.com/group_report?sid=c8dd0df9a67de32742d6f35764c5920946026cb2a0558da1b882d2d818f20c84


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

Android Nexus5 Perf

rendering.mobile - Benchmark documentation link:
  https://bit.ly/rendering-benchmarks

📍 Pinpoint job started.
https://pinpoint-dot-chromeperf.appspot.com/job/14ac4875640000

📍 Found significant differences after each of 3 commits.
https://pinpoint-dot-chromeperf.appspot.com/job/14ac4875640000

Roll src/third_party/skia b8e125281d50..4f94ef6cbd26 (4 commits) by chromium-autoroll@skia-public.iam.gserviceaccount.com
https://chromium.googlesource.com/chromium/src/+/9e370c4631a403f35e0c5d80761cb43582649692
203.6 → 218.5 (+14.96)

Remove a large amount of plumbing in UI compositor by mdjones@chromium.org
https://chromium.googlesource.com/chromium/src/+/fffc2a9d17cb1af7edb6cc640b3171e25955f356
218.5 → 219.6 (+1.114)

WorkerTaskQueue.postTask() doesn't handle all task results correctly. by japhet@chromium.org
https://chromium.googlesource.com/chromium/src/+/991a06f7b39f6f1f1cee7a7d32e980a97fa0d875
218.3 → 220.2 (+1.888)

Understanding performance regressions:
  http://g.co/ChromePerformanceRegressions

Benchmark documentation link:
  https://bit.ly/rendering-benchmarks

The code in my CL is entirely behind a flag, so it's very unlikely to be responsible.

mdjones: is there any chance this is from your CL, or is likely to be the skia roll?

My patch removed some unused plumbing from the tab switcher; I'd be very surprised if that was the issue. The skia roll appears to have had the largest impact (203.6 → 218.5 (+14.96)) so I'd guess that. Updating components to include skia.

The list of patches included in that roll is here: https://skia.googlesource.com/skia.git/+log/b8e125281d50..4f94ef6cbd26