According to this startup profile, AddonRepository.jsm runs during startup and imports osfile.jsm. We should migrate this to the new IOUtils replacement for osfile.jsm when possible.

Stack:

(root) []
XREMain::XRE_main []
XREMain::XRE_main(int, char**, mozilla::BootstrapConfig const&) [libxul.so]
XREMain::XRE_mainRun() [libxul.so]
nsAppStartup::Run() [libxul.so]
nsBaseAppShell::Run() [libxul.so]
MessageLoop::Run() [libxul.so]
mozilla::ipc::MessagePump::Run(base::MessagePump::Delegate*) [libxul.so]
nsThread::ProcessNextEvent(bool, bool*) [libxul.so]
mozilla::dom::(anonymous namespace)::IdleDispatchRunnable::Run() [libxul.so]
mozilla::dom::CallbackObject::CallSetup::~CallSetup() [libxul.so]
<name omitted> [libxul.so]
promise callback []
mozilla::PromiseJobRunnable::Run(mozilla::AutoSlowOperation&) [libxul.so]
mozilla::dom::PromiseJobCallback::Call(mozilla::dom::BindingCallContext&, JS::Handle<JS::Value>, mozilla::ErrorResult&) [libxul.so]
JS::Call(JSContext*, JS::Handle<JS::Value>, JS::Handle<JS::Value>, JS::HandleValueArray const&, JS::MutableHandle<JS::Value>) [libxul.so]
js::InternalCallOrConstruct(JSContext*, JS::CallArgs const&, js::MaybeConstruct, js::CallReason) [libxul.so]
PromiseReactionJob(JSContext*, unsigned int, JS::Value*) [libxul.so]
js::Call(JSContext*, JS::Handle<JS::Value>, JS::Handle<JS::Value>, js::AnyInvokeArgs const&, JS::MutableHandle<JS::Value>, js::CallReason) [libxul.so]
js::RunScript []
getAddon/< [resource://gre/modules/addons/XPIDatabase.jsm:2017:12]
getRepositoryAddon [resource://gre/modules/addons/XPIDatabase.jsm:226:33]
getCachedAddonByID [resource://gre/modules/addons/AddonRepository.jsm:375:26]
openConnection [resource://gre/modules/addons/AddonRepository.jsm:746:16]
> openConnection/this.connectionPromise< [resource://gre/modules/addons/AddonRepository.jsm:748:38]
js::InternalCallOrConstruct(JSContext*, JS::CallArgs const&, js::MaybeConstruct, js::CallReason) [libxul.so]
Interpret(JSContext*, js::RunState&) [libxul.so]
js::NativeGetExistingProperty(JSContext*, JS::Handle<JSObject*>, JS::Handle<js::NativeObject*>, JS::Handle<js::Shape*>, JS::MutableHandle<JS::Value>) [libxul.so]
js::CallGetter(JSContext*, JS::Handle<JS::Value>, JS::Handle<JS::Value>, JS::MutableHandle<JS::Value>) [libxul.so]
js::InternalCallOrConstruct(JSContext*, JS::CallArgs const&, js::MaybeConstruct, js::CallReason) [libxul.so]
mozilla::dom::module_getter::ModuleGetter(JSContext*, unsigned int, JS::Value*) [libxul.so]
mozJSComponentLoader::Import(JSContext*, nsTSubstring<char> const&, JS::MutableHandle<JSObject*>, JS::MutableHandle<JSObject*>, bool) [libxul.so]
profiler_get_backtrace() [libxul.so]
Registers::SyncPopulate() [libxul.so]

The following instances of OS.File in AddonRepository.jsm can be replaced by IOUtils equivalents: https://searchfox.org/mozilla-central/rev/d25eb00ab4e90cc0130cd18f303a04cc2a2f8409/toolkit/mozapps/extensions/internal/AddonRepository.jsm#752,772,850,869

https://hg.mozilla.org/mozilla-central/rev/164933b1f5792cb652cb28f06305f1589ef1534f