https://luci-milo.appspot.com/buildbot/chromium.gpu.fyi/Win10%20Debug%20%28Intel%20HD%20530%29/925
https://luci-milo.appspot.com/buildbot/chromium.gpu.fyi/Win10%20Debug%20%28Intel%20HD%20530%29/927
https://luci-milo.appspot.com/buildbot/chromium.gpu.fyi/Win10%20Debug%20%28Intel%20HD%20530%29/932
https://luci-milo.appspot.com/buildbot/chromium.gpu.fyi/Win10%20Debug%20%28Intel%20HD%20530%29/933

sunnyps@, could this be scheduler-related? Feel free to reassign if not.

The enable scheduler CL didn't land because of a couple of issues. One of them was a command buffer proxy bug that's fixed by https://chromium-review.googlesource.com/c/526308/ and the other was a begin frame source DCHECK failure (https://luci-logdog.appspot.com/v/?s=chromium%2Fbb%2Ftryserver.chromium.mac%2Fmac_chromium_rel_ng%2F471303%2F%2B%2Frecipes%2Fsteps%2Fgpu_process_launch_tests_on_ATI_GPU_on_Mac_Retina__with_patch_%2F0%2Fstdout):
[38354:775:0606/160506.836808:FATAL:begin_frame_source.cc(40)] Check failed: args.frame_time >= last_begin_frame_args_.frame_time. 
0   Chromium Framework                  0x000000011f69294c base::debug::StackTrace::StackTrace(unsigned long) + 28
1   Chromium Framework                  0x000000011f6b8b20 logging::LogMessage::~LogMessage() + 224
2   Chromium Framework                  0x0000000120f8f0f8 cc::BeginFrameObserverBase::OnBeginFrame(cc::BeginFrameArgs const&) + 168
3   Chromium Framework                  0x0000000120f91bf2 cc::ExternalBeginFrameSource::AddObserver(cc::BeginFrameObserver*) + 1202
4   Chromium Framework                  0x0000000120f99393 cc::Scheduler::SetupNextBeginFrameIfNeeded() + 83
5   Chromium Framework                  0x0000000120f981d6 cc::Scheduler::ProcessScheduledActions() + 854
6   Chromium Framework                  0x0000000121040956 cc::SingleThreadProxy::SetNeedsCommit() + 150
7   Chromium Framework                  0x0000000120fe5f73 cc::LayerTreeHost::SetNeedsCommit() + 19
8   Chromium Framework                  0x0000000120eea850 cc::Layer::AddDrawableDescendants(int) + 256
9   Chromium Framework                  0x0000000120eeae33 cc::Layer::RemoveChildOrDependent(cc::Layer*) + 259
10  Chromium Framework                  0x0000000120ee9f04 cc::Layer::RemoveFromParent() + 116
11  Chromium Framework                  0x00000001219b2610 ui::Layer::Remove(ui::Layer*) + 256
12  Chromium Framework                  0x00000001219b1f77 ui::Layer::~Layer() + 375
13  Chromium Framework                  0x00000001219b279e ui::Layer::~Layer() + 14
14  Chromium Framework                  0x000000011dc8bcbf content::DelegatedFrameHost::UpdateGutters() + 479
15  Chromium Framework                  0x000000011dc8c8e5 content::DelegatedFrameHost::SubmitCompositorFrame(cc::LocalSurfaceId const&, cc::CompositorFrame) + 1237
16  Chromium Framework                  0x000000011dc88269 content::BrowserCompositorMac::SubmitCompositorFrame(cc::LocalSurfaceId const&, cc::CompositorFrame) + 153
17  Chromium Framework                  0x000000011dabdb38 content::RenderWidgetHostViewMac::SubmitCompositorFrame(cc::LocalSurfaceId const&, cc::CompositorFrame) + 152
18  Chromium Framework                  0x000000011daaedf5 content::RenderWidgetHostImpl::SubmitCompositorFrame(cc::LocalSurfaceId const&, cc::CompositorFrame) + 709
19  Chromium Framework                  0x000000011d2da754 cc::mojom::MojoCompositorFrameSinkStubDispatch::Accept(cc::mojom::MojoCompositorFrameSink*, mojo::Message*) + 708
20  Chromium Framework                  0x000000011f66d278 mojo::InterfaceEndpointClient::HandleValidatedMessage(mojo::Message*) + 824
21  Chromium Framework                  0x000000011f66cc16 mojo::FilterChain::Accept(mojo::Message*) + 150
22  Chromium Framework                  0x000000011f66e505 mojo::InterfaceEndpointClient::HandleIncomingMessage(mojo::Message*) + 117
23  Chromium Framework                  0x000000011f676904 mojo::internal::MultiplexRouter::ProcessIncomingMessage(mojo::Message*, mojo::internal::MultiplexRouter::ClientCallBehavior, base::SingleThreadTaskRunner*) + 884
24  Chromium Framework                  0x000000011f6761cf mojo::internal::MultiplexRouter::Accept(mojo::Message*) + 287
25  Chromium Framework                  0x000000011f66cc16 mojo::FilterChain::Accept(mojo::Message*) + 150
26  Chromium Framework                  0x000000011f6690b9 mojo::Connector::ReadSingleMessage(unsigned int*) + 281
27  Chromium Framework                  0x000000011f6699f1 mojo::Connector::ReadAllAvailableMessages() + 97
28  Chromium Framework                  0x000000011f669899 mojo::Connector::OnHandleReadyInternal(unsigned int) + 137
29  Chromium Framework                  0x000000011f7af247 mojo::SimpleWatcher::OnHandleReady(int, unsigned int) + 343
30  Chromium Framework                  0x000000011f7af6ca void base::internal::Invoker<base::internal::BindState<void (mojo::SimpleWatcher::*)(int, unsigned int), base::WeakPtr<mojo::SimpleWatcher>, int, unsigned int>, void ()>::RunImpl<void (mojo::SimpleWatcher::* const&)(int, unsigned int), std::__1::tuple<base::WeakPtr<mojo::SimpleWatcher>, int, unsigned int> const&, 0ul, 1ul, 2ul>(void (mojo::SimpleWatcher::* const&&&)(int, unsigned int), std::__1::tuple<base::WeakPtr<mojo::SimpleWatcher>, int, unsigned int> const&&&, base::IndexSequence<0ul, 1ul, 2ul>) + 186
31  Chromium Framework                  0x0000000120a95258 ui::WindowResizeHelperMac::WaitForSingleTaskToRun(base::TimeDelta const&) + 456
32  Chromium Framework                  0x000000011daa881b content::RenderWidgetHostImpl::WaitForSurface() + 811
33  Chromium Framework                  0x000000011daa83d2 content::RenderWidgetHostImpl::PauseForPendingResizeOrRepaints() + 98
34  Chromium Framework                  0x000000011dac1656 -[RenderWidgetHostViewCocoa setFrameSize:] + 214
35  AppKit                              0x00007fffa90d92e3 -[NSView setFrame:] + 390
36  Chromium Framework                  0x000000011dbedf7c -[WebContentsViewCocoa setFrameSize:] + 396
37  AppKit                              0x00007fffa90d92e3 -[NSView setFrame:] + 390
38  Chromium Framework                  0x0000000122cdfd5b -[TabContentsContainerView resizeSubviewsWithOldSize:] + 347
39  AppKit                              0x00007fffa90c1bc1 -[NSView setFrameSize:] + 1881
40  AppKit                              0x00007fffa90d92e3 -[NSView setFrame:] + 390
41  AppKit                              0x00007fffa90e571e -[NSView resizeWithOldSuperviewSize:] + 681
42  AppKit                              0x00007fffa90e4fb8 -[NSView resizeSubviewsWithOldSize:] + 360
43  AppKit                              0x00007fffa90c1bc1 -[NSView setFrameSize:] + 1881
44  AppKit                              0x00007fffa90d92e3 -[NSView setFrame:] + 390
45  AppKit                              0x00007fffa90e571e -[NSView resizeWithOldSuperviewSize:] + 681
46  AppKit                              0x00007fffa90e4fb8 -[NSView resizeSubviewsWithOldSize:] + 360
47  AppKit                              0x00007fffa90c1bc1 -[NSView setFrameSize:] + 1881
48  AppKit                              0x00007fffa90d92e3 -[NSView setFrame:] + 390
49  Chromium Framework                  0x0000000122c4aff4 -[DevToolsContainerView adjustSubviews] + 692
50  AppKit                              0x00007fffa90c1bc1 -[NSView setFrameSize:] + 1881
51  AppKit                              0x00007fffa90d92e3 -[NSView setFrame:] + 390
52  AppKit                              0x00007fffa90e571e -[NSView resizeWithOldSuperviewSize:] + 681
53  AppKit                              0x00007fffa90e4fb8 -[NSView resizeSubviewsWithOldSize:] + 360
54  AppKit                              0x00007fffa90c1bc1 -[NSView setFrameSize:] + 1881
55  AppKit                              0x00007fffa90d92e3 -[NSView setFrame:] + 390
56  Chromium Framework                  0x0000000122c2bf05 -[BrowserWindowController(Private) layoutTabContentArea:] + 149
57  Chromium Framework                  0x0000000122c2e55b -[BrowserWindowController(Private) applyLayout:] + 683
58  Chromium Framework                  0x0000000122c2baeb -[BrowserWindowController(Private) layoutSubviews] + 235
59  Chromium Framework                  0x0000000122c267de -[BrowserWindowController resizeView:newHeight:] + 750
60  Chromium Framework                  0x0000000122c83cda -[InfoBarContainerController positionInfoBarsAndRedraw:] + 826
61  Chromium Framework                  0x0000000121ab0304 infobars::InfoBarContainer::OnInfoBarStateChanged(bool) + 52

stanisc@ can you check if this was caused by the recent ExternalBFS changes you made? I'll also investigate meanwhile.

Yes, I think I might have introduced an issue by refactoring
code in begin_frame_source.cc and inverting the condition that 
checked whether to generate MISSED args.

Before the change:

if (!last_args.IsValid() ||
   (last_begin_frame_args_.frame_time > last_args.frame_time)) { 
  // Generate MISSED args here
  ...
}

After the change:

if (last_args.IsValid() &&
    last_begin_frame_args_.frame_time == last_args.frame_time) {
  // SKIP generating MISSED args
  return BeginFrameArgs();
}

If last_begin_frame_args_.frame_time < last_args.frame_time the 
new implementation would now generate MISSED args. The condition
above should be changed to '<='.
Sorry, I didn't realize this condition would be possible. I guess
that might be the case when the same observer gets added to a different
BFS.

I'll get the fix ready ASAP.

Yes, looking at DCHECK message details in #1 it is clear that having <= condition would have prevented this.

current: "frame_time_us": 5231363668.0,
last:    "frame_time_us": 5231363682.0   
         
current: "sequence_number":11826,
last:    "sequence_number":11827

current: "source_id":2,
last:    "source_id":2

current: "subtype":"NORMAL"
last:    "subtype":"MISSED"

current corresponds to last_begin_frame_args_ and last to last_args

I think the reason I made this mistake is due to a difference between ExternalBFS and DelayBasedBFS. DelayBasedBFS stores MISSED args as last_begin_frame_args_ (which would prevent this issue) while ExternalBFS doesn't. Anyway the fix I mentioned above should be sufficient.

Thanks for investigating!

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/25d005fb3364df055d7773cffe7039cfd3d33eca

commit 25d005fb3364df055d7773cffe7039cfd3d33eca
Author: stanisc <stanisc@chromium.org>
Date: Thu Jun 08 01:13:27 2017

Avoid DCHECK in ExternalBeginFrameSource::GetMissedBeginFrameArgs caused by out of order frame time

DCHECK was caused by incorrectly inverting the logical check in
ExternalBeginFrameSource::AddObserver when refactoring the code.

Before the change:

if (!last_args.IsValid() ||
   (last_begin_frame_args_.frame_time > last_args.frame_time)) {
  // Generate MISSED args here
  ...
}

After the change:

if (last_args.IsValid() &&
    last_begin_frame_args_.frame_time == last_args.frame_time) {
  // SKIP generating MISSED args
  return BeginFrameArgs();
}

last_begin_frame_args_.frame_time which is smaller than last_args.frame_time,
while arguably invalid, would now allow this code to generate a MISSED args
and trigger a DCHECK.

I've fixed this by changing the condition above to
last_begin_frame_args_.frame_time <= last_args.frame_time.

I've added a new unit test to cover this specific case.

BUG= 730218 
CQ_INCLUDE_TRYBOTS=master.tryserver.blink:linux_trusty_blink_rel

Review-Url: https://codereview.chromium.org/2930813002
Cr-Commit-Position: refs/heads/master@{#477846}

[modify] https://crrev.com/25d005fb3364df055d7773cffe7039cfd3d33eca/cc/scheduler/begin_frame_source.cc
[modify] https://crrev.com/25d005fb3364df055d7773cffe7039cfd3d33eca/cc/scheduler/begin_frame_source_unittest.cc

Seems to be fixed.