The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/f84a2c31ca189dea6f8213c59226533ad64596a4

commit f84a2c31ca189dea6f8213c59226533ad64596a4
Author: Reilly Grant <reillyg@chromium.org>
Date: Thu Feb 22 20:36:11 2018

Update expectations for idle-callback/test-runner-run-idle-tasks.html

This test is flaky on debug builds.

TBR=szager@chromium.org

Bug: 814889
Change-Id: I121dae17176af0e5f80121e2bebf1cd5c9524b49
Reviewed-on: https://chromium-review.googlesource.com/932545
Reviewed-by: Reilly Grant <reillyg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#538550}
[modify] https://crrev.com/f84a2c31ca189dea6f8213c59226533ad64596a4/third_party/WebKit/LayoutTests/TestExpectations

I'm looking into this.

This test has gotten worse. Now it is crashing in addition to the timeout failures.

Example build:
https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/Mac10.13%20Tests%20%28dbg%29/3733

It also happens on Mojo Linux:
https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/Mojo%20Linux/15356

Output:

STDERR: [5980:775:0701/165848.593210:FATAL:idle_helper.cc(379)] Check failed: new_deadline == idle_period_deadline_ (6091235251 bogo-microseconds vs. 6091219432 bogo-microseconds)
STDERR: 0   libbase.dylib                       0x000000010fdcd01e base::debug::StackTrace::StackTrace(unsigned long) + 174
STDERR: 1   libbase.dylib                       0x000000010fdcd0dd base::debug::StackTrace::StackTrace(unsigned long) + 29
STDERR: 2   libbase.dylib                       0x000000010f9e29bc base::debug::StackTrace::StackTrace() + 28
STDERR: 3   libbase.dylib                       0x000000010fa61a0c logging::LogMessage::~LogMessage() + 460
STDERR: 4   libbase.dylib                       0x000000010fa5f775 logging::LogMessage::~LogMessage() + 21
STDERR: 5   libblink_platform.dylib             0x0000000138375613 blink::scheduler::IdleHelper::State::UpdateState(blink::scheduler::IdleHelper::IdlePeriodState, base::TimeTicks, base::TimeTicks) + 259
STDERR: 6   libblink_platform.dylib             0x00000001383752f2 blink::scheduler::IdleHelper::StartIdlePeriod(blink::scheduler::IdleHelper::IdlePeriodState, base::TimeTicks, base::TimeTicks) + 1362
STDERR: 7   libblink_platform.dylib             0x00000001383be636 blink::scheduler::MainThreadSchedulerImpl::DidCommitFrameToCompositor() + 454
STDERR: 8   libcontent.dylib                    0x0000000115d6abc3 content::RenderWidgetCompositor::DidCommit() + 67
STDERR: 9   libcc.dylib                         0x000000011084f32a cc::LayerTreeHost::CommitComplete() + 42
STDERR: 10  libcc.dylib                         0x00000001109c271f cc::SingleThreadProxy::CommitComplete() + 287
STDERR: 11  libcc.dylib                         0x00000001109c4e45 cc::SingleThreadProxy::DidActivateSyncTree() + 21
STDERR: 12  libcc.dylib                         0x00000001108a7db7 cc::LayerTreeHostImpl::ActivateSyncTree() + 3127
STDERR: 13  libcc.dylib                         0x00000001109c6300 cc::SingleThreadProxy::CompositeImmediately(base::TimeTicks, bool) + 1376
STDERR: 14  libcc.dylib                         0x0000000110852726 cc::LayerTreeHost::Composite(base::TimeTicks, bool) + 454
STDERR: 15  libcontent.dylib                    0x0000000115d682fb content::RenderWidgetCompositor::SynchronouslyComposite(bool, std::__1::unique_ptr<cc::SwapPromise, std::__1::default_delete<cc::SwapPromise> >) + 1515
STDERR: 16  libcontent.dylib                    0x0000000115d6965c content::RenderWidgetCompositor::SynchronouslyCompositeNoRasterForTesting() + 236
STDERR: 17  libblink_core.dylib                 0x0000000130420d29 blink::WebViewImpl::UpdateAllLifecyclePhasesAndCompositeForTesting() + 57
STDERR: 18  libtest_runner.dylib                0x00000001420ab34d test_runner::WebWidgetTestClient::AnimateNow() + 77

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/9e7eeb2beef9a787f9d24a38e1ecb0bfd64c839b

commit 9e7eeb2beef9a787f9d24a38e1ecb0bfd64c839b
Author: Matt Falkenhagen <falken@chromium.org>
Date: Mon Jul 02 04:49:41 2018

Gardening: Widen expectation of test-runner-run-idle-tasks.html

It also fails on non-Debug and crashes.

Bug: 814889
Change-Id: Ie6f68ec4eeb89df638478c0b2da3b0dc8273d6ee
TBR: altimin@chromium.org
NOTRY: true
Reviewed-on: https://chromium-review.googlesource.com/1121950
Reviewed-by: Matt Falkenhagen <falken@chromium.org>
Commit-Queue: Matt Falkenhagen <falken@chromium.org>
Cr-Commit-Position: refs/heads/master@{#571819}
[modify] https://crrev.com/9e7eeb2beef9a787f9d24a38e1ecb0bfd64c839b/third_party/WebKit/LayoutTests/TestExpectations