I encountered this when I tried to run debug build on Slate.
This may be intentional as this is during startup, in which case, we should allow it.

chrome: ToT {#605939}
platform: 11231.0.0

[12329:12329:1107/064202.159794:WARNING:memory_kills_monitor.cc(174)] Monitoring has been started
[12329:12415:1107/064202.166448:WARNING:simple_synchronous_entry.cc(1251)] Could not open platform files for entry.
device-enumerator: scan all dirs
  device-enumerator: scanning /sys/bus
  device-enumerator: scanning /sys/class
[12329:12369:1107/064202.413814:ERROR:connection_factory_impl.cc(411)] Failed to connect to MCS endpoint with error -106
[12329:12329:1107/064203.124026:FATAL:thread_restrictions.cc(34)] Check failed: !g_blocking_disallowed.Get().Get(). Function marked as blocking was called from a scope that disallows blocking! If this task is running inside the TaskScheduler, it needs to have MayBlock() in its TaskTraits. Otherwise, consider making this blocking work asynchronous or, as a last resort, you may use ScopedAllowBlocking (see its documentation for best practices).
#0 0x7eb04f464f08 base::debug::StackTrace::StackTrace()
#1 0x7eb04f12fbdc base::debug::StackTrace::StackTrace()
#2 0x7eb04f1a189a logging::LogMessage::~LogMessage()
#3 0x7eb04f39df1b base::internal::AssertBlockingAllowed()
#4 0x7eb04f38d640 base::ScopedBlockingCall::ScopedBlockingCall()
#5 0x7eb04f47bc67 base::OpenFile()
#6 0x7eb04f1711dd base::ReadFileToStringWithMaxSize()
#7 0x7eb04f171984 base::ReadFileToString()
#8 0x7eb04f17db87 JSONFileValueDeserializer::ReadFileToString()
#9 0x7eb04f17dfdb JSONFileValueDeserializer::Deserialize()
#10 0x58da74230487 rlz_lib::RlzValueStoreChromeOS::ReadStore()
#11 0x58da742302f9 rlz_lib::RlzValueStoreChromeOS::RlzValueStoreChromeOS()
#12 0x58da742379ef rlz_lib::ScopedRlzValueStoreLock::ScopedRlzValueStoreLock()
#13 0x58da74241dc2 rlz_lib::UpdateExistingAccessPointRlz()
#14 0x58da7bae01a9 rlz::RLZTracker::Init()
#15 0x58da7badfa57 rlz::RLZTracker::InitRlzDelayed()
#16 0x58da75b46be9 chromeos::UserSessionManager::InitRlzImpl()
#17 0x58da73cfa232 _ZN4base8internal13FunctorTraitsIMN10extensions21app_file_handler_util17MimeTypeCollectorEFvmRKNSt3__112basic_stringIcNS5_11char_traitsIcEENS5_9allocatorIcEEEEEvE6InvokeISF_RKNS_7WeakPtrIS4_EEJRKmSD_EEEvT_OT0_DpOT1_
#18 0x58da75410d75 _ZN4base8internal12InvokeHelperILb1EvE8MakeItSoIMN3arc22ArcAppShortcutsRequestEFvmRKN3gfx9ImageSkiaEENS_7WeakPtrIS5_EEJmS9_EEEvOT_OT0_DpOT1_
#19 0x58da75b58f5d _ZN4base8internal7InvokerINS0_9BindStateIMN8chromeos18UserSessionManagerEFvP7ProfileRKNS4_13RlzInitParamsEEJNS_7WeakPtrIS4_EES6_EEEFvS9_EE7RunImplIRKSB_RKNSt3__15tupleIJSD_S6_EEEJLm0ELm1EEEEvOT_OT0_NSK_16integer_sequenceImJXspT1_EEEES9_
#20 0x58da75b58e54 _ZN4base8internal7InvokerINS0_9BindStateIMN8chromeos18UserSessionManagerEFvP7ProfileRKNS4_13RlzInitParamsEEJNS_7WeakPtrIS4_EES6_EEEFvS9_EE3RunEPNS0_13BindStateBaseES9_
#21 0x58da72ce4d7c _ZNO4base12OnceCallbackIFvRK18WebApplicationInfoEE3RunES3_
#22 0x58da736ce2e8 base::internal::ReplyAdapter<>()
#23 0x58da73684809 _ZN4base8internal13FunctorTraitsIPFvNS_12OnceCallbackIFNSt3__110unique_ptrIKN10extensions17ContentHashReaderENS3_14default_deleteIS7_EEEEvEEEPNS4_ISA_NS8_ISA_EEEEEvE6InvokeISH_JSC_SF_EEEvOT_DpOT0_
#24 0x58da75b59ced _ZN4base8internal12InvokeHelperILb0EvE8MakeItSoIPFvNS_12OnceCallbackIFvRKN8chromeos18UserSessionManager13RlzInitParamsEEEEPNSt3__110unique_ptrIS7_NSC_14default_deleteIS7_EEEEEJSB_SH_EEEvOT_DpOT0_
#25 0x58da75b59c8f _ZN4base8internal7InvokerINS0_9BindStateIPFvNS_12OnceCallbackIFvRKN8chromeos18UserSessionManager13RlzInitParamsEEEEPNSt3__110unique_ptrIS6_NSB_14default_deleteIS6_EEEEEJSA_NS0_12OwnedWrapperISF_EEEEEFvvEE7RunImplISI_NSB_5tupleIJSA_SK_EEEJLm0ELm1EEEEvOT_OT0_NSB_16integer_sequenceImJXspT1_EEEE
#26 0x58da75b59b89 _ZN4base8internal7InvokerINS0_9BindStateIPFvNS_12OnceCallbackIFvRKN8chromeos18UserSessionManager13RlzInitParamsEEEEPNSt3__110unique_ptrIS6_NSB_14default_deleteIS6_EEEEEJSA_NS0_12OwnedWrapperISF_EEEEEFvvEE7RunOnceEPNS0_13BindStateBaseE
#27 0x7eb04f0dabbc _ZNO4base12OnceCallbackIFvvEE3RunEv
#28 0x7eb04f38ccc4 base::(anonymous namespace)::PostTaskAndReplyRelay::RunReply()
#29 0x7eb04f38d033 _ZN4base8internal13FunctorTraitsIPFvNS_12_GLOBAL__N_121PostTaskAndReplyRelayEEvE6InvokeIS5_JS3_EEEvOT_DpOT0_
#30 0x7eb04f38cf9d _ZN4base8internal12InvokeHelperILb0EvE8MakeItSoIPFvNS_12_GLOBAL__N_121PostTaskAndReplyRelayEEJS5_EEEvOT_DpOT0_
#31 0x7eb04f38cf60 _ZN4base8internal7InvokerINS0_9BindStateIPFvNS_12_GLOBAL__N_121PostTaskAndReplyRelayEEJS4_EEEFvvEE7RunImplIS6_NSt3__15tupleIJS4_EEEJLm0EEEEvOT_OT0_NSB_16integer_sequenceImJXspT1_EEEE
#32 0x7eb04f38cea9 _ZN4base8internal7InvokerINS0_9BindStateIPFvNS_12_GLOBAL__N_121PostTaskAndReplyRelayEEJS4_EEEFvvEE7RunOnceEPNS0_13BindStateBaseE
#33 0x7eb04f0dabbc _ZNO4base12OnceCallbackIFvvEE3RunEv
#34 0x7eb04f131358 base::debug::TaskAnnotator::RunTask()
#35 0x7eb04f1cd816 base::MessageLoopImpl::RunTask()
#36 0x7eb04f1cdbbe base::MessageLoopImpl::DeferOrRunPendingTask()
#37 0x7eb04f1ce389 base::MessageLoopImpl::DoWork()
#38 0x7eb04f4bd3e5 base::MessagePumpLibevent::Run()
#39 0x7eb04f1ccf0b base::MessageLoopImpl::Run()
#40 0x7eb04f280a7d base::RunLoop::Run()
#41 0x58da76f3b9b3 ChromeBrowserMainParts::MainMessageLoopRun()
#42 0x7eb048971691 content::BrowserMainLoop::RunMainMessageLoopParts()
#43 0x7eb04897aaa0 content::BrowserMainRunnerImpl::Run()
#44 0x7eb04896402b content::BrowserMain()
#45 0x7eb04af6e877 content::RunBrowserProcessMain()
#46 0x7eb04af71f33 content::ContentMainRunnerImpl::RunServiceManager()
#47 0x7eb04af70aaf content::ContentMainRunnerImpl::Run()
#48 0x7eb04af65d1c content::ContentServiceManagerMainDelegate::RunEmbedderProcess()
#49 0x7eb01a82cf5a service_manager::Main()
#50 0x7eb04af6c213 content::ContentMain()
#51 0x58da72cb6858 ChromeMain
#52 0x58da72cb6742 main
#53 0x7eb01c942736 __libc_start_main
#54 0x58da72cb65e9 _start