Stack below. ToT as of today, r418662

Build chrome with oxygen, run on linux desktop with:

out_oxygen/Default/chrome --user-data-dir=/w/udd3 --ash-debug-shortcuts --no-sandbox --ash-pen-palette --login-screen=login --no-first-run --stub-cros --login-profile=user --webui-login --login-manager --webui-gaia-login --parallel-auth --oobe-skip-postlogin -skip-oauth-login -lang=en --enable-experimental-apis --auth-ext-path=/w/chrome/src/platform/assets/gaia_auth --mash

It's possible I have a command line flag wrong, but I suspect this is just a regression.

Thanks to xiyuan for volunteering to help us out with some login stuff!

[21331:21331:0914/143021:ERROR:oobe_ui.cc(600)] Not implemented reached in virtual void chromeos::OobeUI::OnCurrentScreenChanged(const std::string &)
[21331:21331:0914/143021:FATAL:keyboard_driven_event_rewriter.cc(37)] Check failed: instance. 
#0 0x7f68c346871e base::debug::StackTrace::StackTrace()
#1 0x7f68c34cbd9c logging::LogMessage::~LogMessage()
#2 0x7f68c54064cd chromeos::KeyboardDrivenEventRewriter::GetInstance()
#3 0x7f68c9025e25 chromeos::CoreOobeHandler::HandleUpdateCurrentScreen()
#4 0x7f68c45e1029 _ZN4base8internal13FunctorTraitsIMN10extensions15ValueStoreCacheEFvRKSsEvE6InvokeIPS3_JS5_EEEvS7_OT_DpOT0_
#5 0x7f68c45e0f66 _ZN4base8internal12InvokeHelperILb0EvE8MakeItSoIRKMN10extensions15ValueStoreCacheEFvRKSsEJPS5_S7_EEEvOT_DpOT0_
#6 0x7f68c9028e97 _ZN4base8internal7InvokerINS0_9BindStateIMN8chromeos15CoreOobeHandlerEFvRKSsEJNS0_17UnretainedWrapperIS4_EEEEEFvS6_EE7RunImplIRKS8_RKSt5tupleIJSA_EEJLm0EEEEvOT_OT0_NS_13IndexSequenceIJXspT1_EEEES6_
#7 0x7f68c9028dcc _ZN4base8internal7InvokerINS0_9BindStateIMN8chromeos15CoreOobeHandlerEFvRKSsEJNS0_17UnretainedWrapperIS4_EEEEEFvS6_EE3RunEPNS0_13BindStateBaseES6_
#8 0x7f68c41cdec6 base::internal::RunMixin<>::Run()
#9 0x7f68c8bee76d _ZN5login18DispatchToCallbackIJRKSsEJLm0EEEEvRKN4base8CallbackIFvDpT_ELNS3_8internal8CopyModeE1ELNS8_10RepeatModeE1EEEPKNS3_9ListValueENS3_13IndexSequenceIJXspT0_EEEE
#10 0x7f68c8bedfbd _ZN5login15CallbackWrapperIJRKSsEEEvRKN4base8CallbackIFvDpT_ELNS3_8internal8CopyModeE1ELNS8_10RepeatModeE1EEEPKNS3_9ListValueE
#11 0x7f68c425605f _ZN4base8internal13FunctorTraitsIPFvRKNS_8CallbackIFSt10unique_ptrINS_5ValueESt14default_deleteIS4_EEvELNS0_8CopyModeE1ELNS0_10RepeatModeE1EEEPS7_EvE6InvokeIJSD_RKSE_EEEvSG_DpOT_
#12 0x7f68c4691d7d _ZN4base8internal12InvokeHelperILb0EvE8MakeItSoIRKPFvRKNS_8CallbackIFviELNS0_8CopyModeE1ELNS0_10RepeatModeE1EEEPiEJSA_SB_EEEvOT_DpOT0_
#13 0x7f68c8bee477 _ZN4base8internal7InvokerINS0_9BindStateIPFvRKNS_8CallbackIFvRKSsELNS0_8CopyModeE1ELNS0_10RepeatModeE1EEEPKNS_9ListValueEEJS9_EEEFvSE_EE7RunImplIRKSG_RKSt5tupleIJS9_EEJLm0EEEEvOT_OT0_NS_13IndexSequenceIJXspT1_EEEEOSE_
#14 0x7f68c8bee3ac _ZN4base8internal7InvokerINS0_9BindStateIPFvRKNS_8CallbackIFvRKSsELNS0_8CopyModeE1ELNS0_10RepeatModeE1EEEPKNS_9ListValueEEJS9_EEEFvSE_EE3RunEPNS0_13BindStateBaseEOSE_
#15 0x7f68bcfe2176 base::internal::RunMixin<>::Run()
#16 0x7f68be53304b content::WebUIImpl::ProcessWebUIMessage()
#17 0x7f68be531e6d content::WebUIImpl::OnWebUISend()
#18 0x7f68be4f3d8b _ZN4base20DispatchToMethodImplIPN7content15WebContentsImplEMS2_FvRK4GURLRKSsRKNS_9ListValueEERKSt5tupleIJS4_SsS9_EEJLm0ELm1ELm2EEEEvRKT_T0_OT1_NS_13IndexSequenceIJXspT2_EEEE
#19 0x7f68be535818 _ZN4base16DispatchToMethodIPN7content9WebUIImplEMS2_FvRK4GURLRKSsRKNS_9ListValueEERKSt5tupleIJS4_SsS9_EEEEvRKT_T0_OT1_
#20 0x7f68be53579f _ZN3IPC16DispatchToMethodIN7content9WebUIImplEMS2_FvRK4GURLRKSsRKN4base9ListValueEEvSt5tupleIJS3_SsS9_EEEEvPT_T0_PT1_RKT2_
#21 0x7f68be533b0b _ZN3IPC8MessageTI26ViewHostMsg_WebUISend_MetaSt5tupleIJ4GURLSsN4base9ListValueEEEvE8DispatchIN7content9WebUIImplESA_vMSA_FvRKS3_RKSsRKS5_EEEbPKNS_7MessageEPT_PT0_PT1_T2_
#22 0x7f68be531cb2 content::WebUIImpl::OnMessageReceived()
#23 0x7f68be4c8b86 content::WebContentsImpl::OnMessageReceived()
#24 0x7f68be4c8a54 content::WebContentsImpl::OnMessageReceived()
#25 0x7f68be1ea56a content::RenderViewHostImpl::OnMessageReceived()
#26 0x7f68be1fe744 content::RenderWidgetHostImpl::OnMessageReceived()
#27 0x7f68be1b17b1 content::RenderProcessHostImpl::OnMessageReceived()
#28 0x7f68bbe2d2e8 IPC::ChannelProxy::Context::OnDispatchMessage()
#29 0x7f68bbe3371b _ZN4base8internal13FunctorTraitsIMN3IPC12ChannelProxy7ContextEFvRKNS2_7MessageEEvE6InvokeIRK13scoped_refptrIS4_EJS7_EEEvS9_OT_DpOT0_
#30 0x7f68bbe33606 _ZN4base8internal12InvokeHelperILb0EvE8MakeItSoIRKMN3IPC12ChannelProxy7ContextEFvRKNS4_7MessageEEJRK13scoped_refptrIS6_ES9_EEEvOT_DpOT0_
#31 0x7f68bbe33593 _ZN4base8internal7InvokerINS0_9BindStateIMN3IPC12ChannelProxy7ContextEFvRKNS3_7MessageEEJ13scoped_refptrIS5_ES6_EEEFvvEE7RunImplIRKSA_RKSt5tupleIJSC_S6_EEJLm0ELm1EEEEvOT_OT0_NS_13IndexSequenceIJXspT1_EEEE
#32 0x7f68bbe334ac _ZN4base8internal7InvokerINS0_9BindStateIMN3IPC12ChannelProxy7ContextEFvRKNS3_7MessageEEJ13scoped_refptrIS5_ES6_EEEFvvEE3RunEPNS0_13BindStateBaseE
#33 0x7f68c343b57b base::internal::RunMixin<>::Run()
#34 0x7f68c346d75b base::debug::TaskAnnotator::RunTask()
#35 0x7f68c34e90e1 base::MessageLoop::RunTask()
#36 0x7f68c34e9364 base::MessageLoop::DeferOrRunPendingTask()
#37 0x7f68c34e962e base::MessageLoop::DoWork()
#38 0x7f68c34ffa4c base::MessagePumpLibevent::Run()
#39 0x7f68c34e8b4a base::MessageLoop::RunHandler()
#40 0x7f68c35825f4 base::RunLoop::Run()
#41 0x7f68c6244f87 ChromeBrowserMainParts::MainMessageLoopRun()