On tip of tree (and probably prior versions), opening Settings in Guest Mode on CrOS-on-Linux causes a CHECK or LOG(FATAL):

[237476:237476:1112/141100.114123:FATAL:account_id.cc(150)] GetAccountIdKey(): no id for {"account_type":"unknown","email":"$guest"}
#0 0x7f3c95cc175f base::debug::StackTrace::StackTrace()
#1 0x7f3c95bf35fb logging::LogMessage::~LogMessage()   
#2 0x558f0efadd4b AccountId::GetAccountIdKey()                                
#3 0x558f0e2f5106 drive::DriveIntegrationService::DriveFsHolder::GetObfuscatedAccountId()
#4 0x7f3c8e23c15b drivefs::DriveFsHost::GetMountPath()
#5 0x558f0e2f0994 drive::DriveIntegrationService::GetMountPointPath()
#6 0x558f0e32cc5c file_manager::util::GetPathDisplayTextForSettings()
#7 0x558f0fef55c9 settings::DownloadsHandler::HandleGetDownloadLocationText()
#8 0x7f3c93122678 content::WebUIImpl::ProcessWebUIMessage()
#9 0x7f3c93121793 _ZN3IPC8MessageTI27FrameHostMsg_WebUISend_MetaNSt3__15tupleIJNS2_12basic_stringIcNS2_11char_traitsIcEENS2_9allocatorIcEEEEN4base9ListValueEEEEvE8DispatchIN7content9We
bUIImplESG_NSF_15RenderFrameHostEMSG_FvPSH_RKS9_RKSB_EEEbPKNS_7MessageEPT_PT0_PT1_T2_
#10 0x7f3c931216dc content::WebUIImpl::OnMessageReceived()            
#11 0x7f3c930d5c34 content::WebContentsImpl::OnMessageReceived()      
#12 0x7f3c92d60194 content::RenderFrameHostImpl::OnMessageReceived()          
#13 0x7f3c92f76f1b content::RenderProcessHostImpl::OnMessageReceived()
#14 0x7f3c94287ba1 IPC::ChannelProxy::Context::OnDispatchMessage()                                                                                                                      #15 0x7f3c9428a48b _ZN4base8internal7InvokerINS0_9BindStateIMN3IPC12ChannelProxy7ContextEFvRKNS3_7MessageEEJ13scoped_refptrIS5_ES6_EEEFvvEE3RunEPNS0_13BindStateBaseE
#16 0x7f3c95bd68ca base::debug::TaskAnnotator::RunTask()  
#17 0x7f3c95c0277f base::MessageLoop::RunTask()                 
#18 0x7f3c95c02b73 base::MessageLoop::DoWork()                      
#19 0x7f3c95ce4f69 base::MessagePumpLibevent::Run()                   
#20 0x7f3c95c02324 base::MessageLoop::Run()                       
#21 0x7f3c95c33e59 base::RunLoop::Run()                                                                                                                              
#22 0x558f0e8dd44d ChromeBrowserMainParts::MainMessageLoopRun()
#23 0x7f3c92bb10c7 content::BrowserMainLoop::RunMainMessageLoopParts()
#24 0x7f3c92bb3c26 content::BrowserMainRunnerImpl::Run()
#25 0x7f3c92bad669 content::BrowserMain()          
#26 0x7f3c9367ac4b content::ContentMainRunnerImpl::RunServiceManager()
#27 0x7f3c9367ab17 content::ContentMainRunnerImpl::Run()
#28 0x7f3c86074e56 service_manager::Main()                     
#29 0x7f3c93679014 content::ContentMain()                             
#30 0x558f0dac0393 ChromeMain                           
#31 0x7f3c8667b2b1 __libc_start_main     
#32 0x558f0dac020a _start                                             

Since this seems Drive related, I suspect https://chromium-review.googlesource.com/1201632 may have broken it.