Restore thread check in KeyedService factories.

components/keyed_service/ios/refcounted_browser_state_keyed_service_factory.cc

Index: components/keyed_service/ios/refcounted_browser_state_keyed_service_factory.cc
diff --git a/components/keyed_service/ios/refcounted_browser_state_keyed_service_factory.cc b/components/keyed_service/ios/refcounted_browser_state_keyed_service_factory.cc
index a9abd88e52634595edea81c6bbdb366872c250e8..f4a6d68f61d9958c3cb01d0e1d6d4a08f6ec983c 100644
--- a/components/keyed_service/ios/refcounted_browser_state_keyed_service_factory.cc
+++ b/components/keyed_service/ios/refcounted_browser_state_keyed_service_factory.cc
@@ -49,9 +49,6 @@ RefcountedBrowserStateKeyedServiceFactory::GetServiceForBrowserState(
 web::BrowserState*
 RefcountedBrowserStateKeyedServiceFactory::GetBrowserStateToUse(
     web::BrowserState* context) const {
-  // TODO(crbug.com/701326): This DCHECK should be moved to GetContextToUse().
-  DCHECK(CalledOnValidThread());
-
   // Safe default for Incognito mode: no service.
   if (context->IsOffTheRecord())
     return nullptr;
@@ -93,6 +90,7 @@ bool RefcountedBrowserStateKeyedServiceFactory::IsOffTheRecord(
 base::SupportsUserData*
 RefcountedBrowserStateKeyedServiceFactory::GetContextToUse(
     base::SupportsUserData* context) const {
+  DCHECK(CalledOnValidThread());
   AssertContextWasntDestroyed(context);
   return GetBrowserStateToUse(static_cast<web::BrowserState*>(context));
 }