Looks like a commit in first week of Feb or last week of January: https://uma.googleplex.com/p/chrome/timeline_v2/?sid=fa64fe130bf791abd83751812584c05c

Great find! I've set up a chirp alert that should fire if this happens again: https://uma.googleplex.com/p//chirp/notification/?filters=channel%2Cone_of%2C4%7C3%7C2%7C1%2Cplatform%2Cone_of%2CA&email=skyostil%40google.com&histograms=RendererScheduler.TaskDurationPerQueueType2.Background.AfterFifthMinute&dates=All&allowAnyRecipient=false

Thanks, Chirp notification sounds like a great idea! Is there a way to filter specifically for timer notifications to avoid noise from when we remove/rename other tasks queues? 

If the answer is no, we probably should create a special histogram for this.

Now I believe that this is working as intended and the problem is that keepalive prevents renderer from being backgrounded per this Shubhie's patch [1] landed Feb 1.

The problem is that keepalive seems to be a very frequent event. We probably want to a) continue stopping timers even when this signal is present and b) revisit this signal for loading tasks.

I'll look into adding more metrics to confirm that, meanwhile I'm assigning this to Shubhie.

[1] https://chromium-review.googlesource.com/c/chromium/src/+/869172

+ojan to comment on priority -- I'm not sure this is a P0.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/f2b39a21d127181a5114857d8c2c886fc1bc1214

commit f2b39a21d127181a5114857d8c2c886fc1bc1214
Author: Alexander Timin <altimin@chromium.org>
Date: Thu Mar 22 17:24:35 2018

[scheduler] Add keep-active in background metrics.

Measure the amount of work done in background when keep-active signal is
present. This is to allow us to test the theory that we stopped stopping
timers in background after 5 minutes on Android due to widespread
keep-active signal.

R=panicker@chromium.org,rkaplow@chromium.org
BUG= 823482 

Change-Id: I653016d795a1903ea9d943e3c2b962ab9c1ba088
Reviewed-on: https://chromium-review.googlesource.com/973225
Reviewed-by: Shubhie Panicker <panicker@chromium.org>
Reviewed-by: Robert Kaplow <rkaplow@chromium.org>
Commit-Queue: Alexander Timin <altimin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#545126}
[modify] https://crrev.com/f2b39a21d127181a5114857d8c2c886fc1bc1214/third_party/WebKit/Source/platform/scheduler/renderer/renderer_metrics_helper.cc
[modify] https://crrev.com/f2b39a21d127181a5114857d8c2c886fc1bc1214/third_party/WebKit/Source/platform/scheduler/renderer/renderer_metrics_helper.h
[modify] https://crrev.com/f2b39a21d127181a5114857d8c2c886fc1bc1214/tools/metrics/histograms/histograms.xml

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/c226de349ba934e3591fb97f2d35b8b4d58ee34b

commit c226de349ba934e3591fb97f2d35b8b4d58ee34b
Author: Shubhie Panicker <panicker@chromium.org>
Date: Tue Mar 27 20:54:12 2018

Add UMA to help investigate long keep alive.

Bug:  823482 
Change-Id: I904a57875d295cb07c99ab2b6a61358108f69d2d
Reviewed-on: https://chromium-review.googlesource.com/974709
Commit-Queue: Shubhie Panicker <panicker@chromium.org>
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Reviewed-by: Alexander Timin <altimin@chromium.org>
Reviewed-by: Ilya Sherman <isherman@chromium.org>
Reviewed-by: Tsuyoshi Horo <horo@chromium.org>
Reviewed-by: Matt Falkenhagen <falken@chromium.org>
Cr-Commit-Position: refs/heads/master@{#546249}
[modify] https://crrev.com/c226de349ba934e3591fb97f2d35b8b4d58ee34b/content/browser/frame_host/keep_alive_handle_factory.cc
[modify] https://crrev.com/c226de349ba934e3591fb97f2d35b8b4d58ee34b/content/browser/renderer_host/render_process_host_impl.cc
[modify] https://crrev.com/c226de349ba934e3591fb97f2d35b8b4d58ee34b/content/browser/renderer_host/render_process_host_impl.h
[modify] https://crrev.com/c226de349ba934e3591fb97f2d35b8b4d58ee34b/content/browser/service_worker/service_worker_process_manager.cc
[modify] https://crrev.com/c226de349ba934e3591fb97f2d35b8b4d58ee34b/content/browser/shared_worker/shared_worker_service_impl.cc
[modify] https://crrev.com/c226de349ba934e3591fb97f2d35b8b4d58ee34b/content/browser/site_per_process_browsertest.cc
[modify] https://crrev.com/c226de349ba934e3591fb97f2d35b8b4d58ee34b/content/public/browser/render_process_host.h
[modify] https://crrev.com/c226de349ba934e3591fb97f2d35b8b4d58ee34b/content/public/test/mock_render_process_host.cc
[modify] https://crrev.com/c226de349ba934e3591fb97f2d35b8b4d58ee34b/content/public/test/mock_render_process_host.h
[modify] https://crrev.com/c226de349ba934e3591fb97f2d35b8b4d58ee34b/tools/metrics/histograms/histograms.xml

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/cb7dacae47149eb10ea639d82d96762ae8ac58f4

commit cb7dacae47149eb10ea639d82d96762ae8ac58f4
Author: Shubhie Panicker <panicker@chromium.org>
Date: Tue Mar 27 21:02:33 2018

Fix incorrect queue-type

Bug:  823482 
Change-Id: I4b5102a59c07100f88c9f442e3c9e642fb116250
Reviewed-on: https://chromium-review.googlesource.com/981311
Commit-Queue: Shubhie Panicker <panicker@chromium.org>
Reviewed-by: Alexander Timin <altimin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#546253}
[modify] https://crrev.com/cb7dacae47149eb10ea639d82d96762ae8ac58f4/third_party/WebKit/Source/platform/scheduler/renderer/frame_scheduler_impl.cc

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/0ea1764907cc5bc5d1a7d500561a0e3af5e3425b

commit 0ea1764907cc5bc5d1a7d500561a0e3af5e3425b
Author: Shubhie Panicker <panicker@chromium.org>
Date: Sat Mar 31 01:34:46 2018

POC for considering keep-active signal for freezing per-frame task queues.

Bug:  823482 
Change-Id: I633fa3fc6be6b04cc9d58a8165fed1bc388f731b
Reviewed-on: https://chromium-review.googlesource.com/981308
Commit-Queue: Shubhie Panicker <panicker@chromium.org>
Reviewed-by: Alexander Timin <altimin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#547352}
[modify] https://crrev.com/0ea1764907cc5bc5d1a7d500561a0e3af5e3425b/third_party/WebKit/Source/platform/scheduler/main_thread/frame_scheduler_impl.cc
[modify] https://crrev.com/0ea1764907cc5bc5d1a7d500561a0e3af5e3425b/third_party/WebKit/Source/platform/scheduler/main_thread/frame_scheduler_impl.h
[modify] https://crrev.com/0ea1764907cc5bc5d1a7d500561a0e3af5e3425b/third_party/WebKit/Source/platform/scheduler/main_thread/frame_scheduler_impl_unittest.cc
[modify] https://crrev.com/0ea1764907cc5bc5d1a7d500561a0e3af5e3425b/third_party/WebKit/Source/platform/scheduler/main_thread/page_scheduler_impl.cc
[modify] https://crrev.com/0ea1764907cc5bc5d1a7d500561a0e3af5e3425b/third_party/WebKit/Source/platform/scheduler/main_thread/page_scheduler_impl.h
[modify] https://crrev.com/0ea1764907cc5bc5d1a7d500561a0e3af5e3425b/third_party/WebKit/Source/platform/scheduler/public/frame_scheduler.h
[modify] https://crrev.com/0ea1764907cc5bc5d1a7d500561a0e3af5e3425b/third_party/WebKit/Source/platform/scheduler/public/page_scheduler.h
[modify] https://crrev.com/0ea1764907cc5bc5d1a7d500561a0e3af5e3425b/third_party/WebKit/Source/platform/scheduler/renderer/main_thread_task_queue.cc
[modify] https://crrev.com/0ea1764907cc5bc5d1a7d500561a0e3af5e3425b/third_party/WebKit/Source/platform/scheduler/renderer/main_thread_task_queue.h
[modify] https://crrev.com/0ea1764907cc5bc5d1a7d500561a0e3af5e3425b/third_party/WebKit/Source/platform/scheduler/renderer/renderer_scheduler_impl.cc
[modify] https://crrev.com/0ea1764907cc5bc5d1a7d500561a0e3af5e3425b/third_party/WebKit/Source/platform/scheduler/renderer/renderer_scheduler_impl.h
[modify] https://crrev.com/0ea1764907cc5bc5d1a7d500561a0e3af5e3425b/third_party/WebKit/Source/platform/scheduler/renderer/renderer_scheduler_impl_unittest.cc
[modify] https://crrev.com/0ea1764907cc5bc5d1a7d500561a0e3af5e3425b/third_party/WebKit/Source/platform/scheduler/test/fake_page_scheduler.h