Restore thread check in KeyedService factories.

components/keyed_service/content/browser_context_keyed_service_factory.cc

Index: components/keyed_service/content/browser_context_keyed_service_factory.cc
diff --git a/components/keyed_service/content/browser_context_keyed_service_factory.cc b/components/keyed_service/content/browser_context_keyed_service_factory.cc
index 38f6ca6158a4314adcaaa3cef11387b6cae12993..a2dad000ddcad6cac02c2b337e01b097dcab1b3c 100644
--- a/components/keyed_service/content/browser_context_keyed_service_factory.cc
+++ b/components/keyed_service/content/browser_context_keyed_service_factory.cc
@@ -48,9 +48,6 @@ KeyedService* BrowserContextKeyedServiceFactory::GetServiceForBrowserContext(
 content::BrowserContext*
 BrowserContextKeyedServiceFactory::GetBrowserContextToUse(
     content::BrowserContext* 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;
@@ -99,6 +96,7 @@ bool BrowserContextKeyedServiceFactory::IsOffTheRecord(
 
 base::SupportsUserData* BrowserContextKeyedServiceFactory::GetContextToUse(
     base::SupportsUserData* context) const {
+  DCHECK(CalledOnValidThread());
   AssertContextWasntDestroyed(context);
   return GetBrowserContextToUse(static_cast<content::BrowserContext*>(context));
 }