On ToT,
- login
- screen lock
- shift-tab several times

causes crash;

[117707:117707:1115/153821.786855:FATAL:views_screen_locker.cc(294)] Check failed: false.
#0 0x7fcc26b6642d base::debug::StackTrace::StackTrace() 
#1 0x7fcc26879e5a base::debug::StackTrace::StackTrace()                            
#2 0x7fcc268e597e logging::LogMessage::~LogMessage()   
#3 0x55aa4702281f chromeos::ViewsScreenLocker::HandleFocusOobeDialog()
#4 0x55aa4d91bf20 LoginScreenClient::FocusOobeDialog()                        
#5 0x7fcc0d84e246 ash::mojom::LoginScreenClientStubDispatch::Accept()
#6 0x55aa4d91d353 ash::mojom::LoginScreenClientStub<>::Accept()
#7 0x7fcc26dba94d mojo::InterfaceEndpointClient::HandleValidatedMessage()
#8 0x7fcc26db93e1 mojo::InterfaceEndpointClient::HandleIncomingMessageThunk::Accept()   
#9 0x7fcc26db78b8 mojo::FilterChain::Accept()                                           
#10 0x7fcc26dbd2e6 mojo::InterfaceEndpointClient::HandleIncomingMessage()               
#11 0x7fcc26dc91d2 mojo::internal::MultiplexRouter::ProcessIncomingMessage()            
#12 0x7fcc26dc87f5 mojo::internal::MultiplexRouter::Accept()                            
#13 0x7fcc26db78b8 mojo::FilterChain::Accept()                        
#14 0x7fcc26daa714 mojo::Connector::ReadSingleMessage()         
#15 0x7fcc26dab6ba mojo::Connector::ReadAllAvailableMessages()            
#16 0x7fcc26dab488 mojo::Connector::OnHandleReadyInternal()                                                              
#17 0x7fcc26dab38b mojo::Connector::OnWatcherHandleReady()
#18 0x7fcc26daedff _ZN4base8internal13FunctorTraitsIMN4mojo9ConnectorEFvjEvE6InvokeIS5_PS3_JjEEEvT_OT0_DpOT1_                                                                                   
#19 0x7fcc26daed5f _ZN4base8internal12InvokeHelperILb0EvE8MakeItSoIRKMN4mojo9ConnectorEFvjEJPS5_jEEEvOT_DpOT0_
#20 0x7fcc26daecf5 _ZN4base8internal7InvokerINS0_9BindStateIMN4mojo9ConnectorEFvjEJNS0_17UnretainedWrapperIS4_EEEEEFvjEE7RunImplIRKS6_RKNSt3__15tupleIJS8_EEEJLm0EEEEvOT_OT0_NSF_16integer_sequen
ceImJXspT1_EEEEOj
#21 0x7fcc26daec1b _ZN4base8internal7InvokerINS0_9BindStateIMN4mojo9ConnectorEFvjEJNS0_17UnretainedWrapperIS4_EEEEEFvjEE3RunEPNS0_13BindStateBaseEj
#22 0x7fcc26da5d2e _ZNKR4base17RepeatingCallbackIFvjEE3RunEj
#23 0x7fcc26dadd8f mojo::SimpleWatcher::DiscardReadyState()
#24 0x7fcc26dadfff _ZN4base8internal13FunctorTraitsIPFvRKNS_17RepeatingCallbackIFvjEEEjRKN4mojo18HandleSignalsStateEEvE6InvokeIRKSC_JS6_jSA_EEEvOT_DpOT0_
#25 0x7fcc26dadf9d _ZN4base8internal12InvokeHelperILb0EvE8MakeItSoIRKPFvRKNS_17RepeatingCallbackIFvjEEEjRKN4mojo18HandleSignalsStateEEJS8_jSC_EEEvOT_DpOT0_
#26 0x7fcc26dadf40 _ZN4base8internal7InvokerINS0_9BindStateIPFvRKNS_17RepeatingCallbackIFvjEEEjRKN4mojo18HandleSignalsStateEEJS5_EEEFvjSB_EE7RunImplIRKSD_RKNSt3__15tupleIJS5_EEEJLm0EEEEvOT_OT0_
NSK_16integer_sequenceImJXspT1_EEEEOjSB_
#27 0x7fcc26dade66 _ZN4base8internal7InvokerINS0_9BindStateIPFvRKNS_17RepeatingCallbackIFvjEEEjRKN4mojo18HandleSignalsStateEEJS5_EEEFvjSB_EE3RunEPNS0_13BindStateBaseEjSB_
#28 0x7fcc26d3b36e _ZNKR4base17RepeatingCallbackIFvjRKN4mojo18HandleSignalsStateEEE3RunEjS4_
#29 0x7fcc26d3ad0b mojo::SimpleWatcher::OnHandleReady()
#30 0x7fcc26d3bb23 _ZN4base8internal13FunctorTraitsIMN4mojo13SimpleWatcherEFvijRKNS2_18HandleSignalsStateEEvE6InvokeIS8_RKNS_7WeakPtrIS3_EEJRKiRKjS6_EEEvT_OT0_DpOT1_
#31 0x7fcc26d3ba65 _ZN4base8internal12InvokeHelperILb1EvE8MakeItSoIRKMN4mojo13SimpleWatcherEFvijRKNS4_18HandleSignalsStateEERKNS_7WeakPtrIS5_EEJRKiRKjS8_EEEvOT_OT0_DpOT1_
#32 0x7fcc26d3b9c2 _ZN4base8internal7InvokerINS0_9BindStateIMN4mojo13SimpleWatcherEFvijRKNS3_18HandleSignalsStateEEJNS_7WeakPtrIS4_EEijS5_EEEFvvEE7RunImplIRKS9_RKNSt3__15tupleIJSB_ijS5_EEEJLm0E
Lm1ELm2ELm3EEEEvOT_OT0_NSI_16integer_sequenceImJXspT1_EEEE
#33 0x7fcc26d3b80c _ZN4base8internal7InvokerINS0_9BindStateIMN4mojo13SimpleWatcherEFvijRKNS3_18HandleSignalsStateEEJNS_7WeakPtrIS4_EEijS5_EEEFvvEE3RunEPNS0_13BindStateBaseE
#34 0x7fcc2682bdbe _ZNO4base12OnceCallbackIFvvEE3RunEv
#35 0x7fcc2687b2aa base::debug::TaskAnnotator::RunTask()
#36 0x7fcc2690b79c base::MessageLoopImpl::RunTask()
#37 0x7fcc2690ba9b base::MessageLoopImpl::DeferOrRunPendingTask()
#38 0x7fcc2690c0b4 base::MessageLoopImpl::DoWork()
#39 0x7fcc26bb8269 base::MessagePumpLibevent::Run()
#40 0x7fcc2690afb6 base::MessageLoopImpl::Run()
#41 0x7fcc269b2612 base::RunLoop::Run()