Chrome Version: 63.0.3222.1
OS: Win10

I'm getting a DCHECK due to violating IOAllowed restriction on the main thread in the component updater.

// Tell the rest of the world where to find the platform-specific PNaCl files.
void OverrideDirPnaclComponent(const base::FilePath& base_path) {
  PathService::Override(chrome::DIR_PNACL_COMPONENT, GetPlatformDir(base_path));  << HERE, inside ::Override(...)
}

0:000> kc
  *** Stack trace for last set context - .thread/.cxr resets it
 # 
00 chrome_64480000!base::debug::BreakDebugger
01 chrome_64480000!logging::LogMessage::~LogMessage
02 chrome_64480000!base::ThreadRestrictions::AssertIOAllowed
03 chrome_64480000!base::PathExists
04 chrome_64480000!base::PathService::OverrideAndCreateIfNeeded
05 chrome_64480000!base::PathService::Override
06 chrome_64480000!component_updater::?A0xc03ab486::OverrideDirPnaclComponent
07 chrome_64480000!component_updater::`anonymous namespace'::PnaclComponentInstallerTraits::ComponentReady
08 chrome_64480000!component_updater::DefaultComponentInstaller::ComponentReady
09 chrome_64480000!component_updater::DefaultComponentInstaller::FinishRegistration
0a chrome_64480000!base::internal::FunctorTraits<void (__thiscall component_updater::DefaultComponentInstaller::*)(scoped_refptr<component_updater::DefaultComponentInstaller::RegistrationInfo> const &,component_updater::ComponentUpdateService *,base::RepeatingCallback<void __cdecl(void)> const &),void>::Invoke
0b chrome_64480000!base::internal::InvokeHelper<0,void>::MakeItSo
0c chrome_64480000!base::internal::Invoker<base::internal::BindState<void (__thiscall component_updater::DefaultComponentInstaller::*)(scoped_refptr<component_updater::DefaultComponentInstaller::RegistrationInfo> const &,component_updater::ComponentUpdateService *,base::RepeatingCallback<void __cdecl(void)> const &),scoped_refptr<component_updater::DefaultComponentInstaller>,scoped_refptr<component_updater::DefaultComponentInstaller::RegistrationInfo>,component_updater::ComponentUpdateService *,base::RepeatingCallback<void __cdecl(void)> >,void __cdecl(void)>::RunImpl<void (__thiscall component_updater::DefaultComponentInstaller::*const &)(scoped_refptr<component_updater::DefaultComponentInstaller::RegistrationInfo> const &,component_updater::ComponentUpdateService *,base::RepeatingCallback<void __cdecl(void)> const &),std::tuple<scoped_refptr<component_updater::DefaultComponentInstaller>,scoped_refptr<component_updater::DefaultComponentInstaller::RegistrationInfo>,component_updater::ComponentUpdateService *,base::RepeatingCallback<void __cdecl(void)> > const &,0,1,2,3>
0d chrome_64480000!base::internal::Invoker<base::internal::BindState<void (__thiscall component_updater::DefaultComponentInstaller::*)(scoped_refptr<component_updater::DefaultComponentInstaller::RegistrationInfo> const &,component_updater::ComponentUpdateService *,base::RepeatingCallback<void __cdecl(void)> const &),scoped_refptr<component_updater::DefaultComponentInstaller>,scoped_refptr<component_updater::DefaultComponentInstaller::RegistrationInfo>,component_updater::ComponentUpdateService *,base::RepeatingCallback<void __cdecl(void)> >,void __cdecl(void)>::Run
0e chrome_64480000!base::OnceCallback<void __cdecl(void)>::Run
0f chrome_64480000!base::`anonymous namespace'::PostTaskAndReplyRelay::RunReplyAndSelfDestruct
10 chrome_64480000!base::OnceCallback<void __cdecl(void)>::Run
11 chrome_64480000!base::debug::TaskAnnotator::RunTask
12 chrome_64480000!base::internal::IncomingTaskQueue::RunTask
13 chrome_64480000!base::MessageLoop::RunTask
14 chrome_64480000!base::MessageLoop::DeferOrRunPendingTask
15 chrome_64480000!base::MessageLoop::DoWork
16 chrome_64480000!base::MessagePumpForUI::DoRunLoop
17 chrome_64480000!base::MessagePumpWin::Run
18 chrome_64480000!base::MessageLoop::Run
19 chrome_64480000!base::RunLoop::Run
1a chrome_64480000!ChromeBrowserMainParts::MainMessageLoopRun
1b chrome_64480000!content::BrowserMainLoop::RunMainMessageLoopParts
1c chrome_64480000!content::BrowserMainRunnerImpl::Initialize
1d chrome_64480000!content::BrowserMain
1e chrome_64480000!content::RunNamedProcessTypeMain
1f chrome_64480000!content::ContentMainRunnerImpl::Run
20 chrome_64480000!service_manager::Main
21 chrome_64480000!content::ContentMain
22 chrome_64480000!ChromeMain