The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/957b034333640c832f432f6d9cdb2f3ef260fd5b

commit 957b034333640c832f432f6d9cdb2f3ef260fd5b
Author: Jeffrey Yasskin <jyasskin@chromium.org>
Date: Fri Dec 07 01:19:44 2018

Revert "Change interleaving of delayed and immediate tasks to match MessageLoop"

This reverts commit dda57a2c6aa319675172f8558ce8c24d9333f894.

Reason for revert: Made http/tests/devtools/sources/debugger-breakpoints/restore-locations-for-breakpoint-with-broken-source-map.js flaky, according to https://crbug.com/912614.

Original change's description:
> Change interleaving of delayed and immediate tasks to match MessageLoop
> 
> Previously the TaskQueueSelector would allow up to 3 delayed tasks to
> run for every immediate task if both where ready to run.  This patch
> changes it to a 1:1 ratio like the MessageLoop.  NB neither the
> SequenceManager nor the MessageLoop allow delayed tasks to skip ahead
> of immediate tasks.
> 
> In addition I've removed the PrioritizingSelector inner class which makes
> the code a bit more readable.  In addition based on review comments I
> changed the style of functions to return a pointer to the WorkQueue or
> null rather than a bool. This in general improves readability.
> 
> Bug: 863341, 891670
> Change-Id: I61d4f118880f109c01ad4a2d5301acc9103b0b35
> Reviewed-on: https://chromium-review.googlesource.com/c/1361103
> Commit-Queue: Alex Clarke <alexclarke@chromium.org>
> Reviewed-by: Sami Kyöstilä <skyostil@chromium.org>
> Reviewed-by: Alexander Timin <altimin@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#614329}

TBR=skyostil@chromium.org,alexclarke@chromium.org,altimin@chromium.org

Change-Id: I2b92bee12bfdd05fac12955655106253cab0d1e6
No-Presubmit: true
Bug: 863341, 891670, 912614
Reviewed-on: https://chromium-review.googlesource.com/c/1366223
Reviewed-by: Jeffrey Yasskin <jyasskin@chromium.org>
Commit-Queue: Jeffrey Yasskin <jyasskin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#614545}
[modify] https://crrev.com/957b034333640c832f432f6d9cdb2f3ef260fd5b/base/task/sequence_manager/sequence_manager_impl.cc
[modify] https://crrev.com/957b034333640c832f432f6d9cdb2f3ef260fd5b/base/task/sequence_manager/sequence_manager_impl.h
[modify] https://crrev.com/957b034333640c832f432f6d9cdb2f3ef260fd5b/base/task/sequence_manager/sequence_manager_impl_unittest.cc
[modify] https://crrev.com/957b034333640c832f432f6d9cdb2f3ef260fd5b/base/task/sequence_manager/task_queue_selector.cc
[modify] https://crrev.com/957b034333640c832f432f6d9cdb2f3ef260fd5b/base/task/sequence_manager/task_queue_selector.h
[modify] https://crrev.com/957b034333640c832f432f6d9cdb2f3ef260fd5b/base/task/sequence_manager/task_queue_selector_unittest.cc
[modify] https://crrev.com/957b034333640c832f432f6d9cdb2f3ef260fd5b/base/task/sequence_manager/work_queue_sets.cc
[modify] https://crrev.com/957b034333640c832f432f6d9cdb2f3ef260fd5b/base/task/sequence_manager/work_queue_sets.h
[modify] https://crrev.com/957b034333640c832f432f6d9cdb2f3ef260fd5b/base/task/sequence_manager/work_queue_sets_unittest.cc
[modify] https://crrev.com/957b034333640c832f432f6d9cdb2f3ef260fd5b/base/task/sequence_manager/work_queue_unittest.cc
[modify] https://crrev.com/957b034333640c832f432f6d9cdb2f3ef260fd5b/third_party/blink/web_tests/http/tests/devtools/sources/debugger/debugger-scope-resolve-this-expected.txt