Fix SetTestingFactoryAndUse for BSKSF

The documentation says that the parameter must not be empty, so
add a DCHECK instead of a check. This is safe as the underlying
method in KSF DCHECK too.

Bug: 809610
Change-Id: Ib7c8b15d1bbc3f82ee3403f530a0167020cfee53
Reviewed-on: https://chromium-review.googlesource.com/1248629Reviewed-by: Colin Blundell <blundell@chromium.org>
Commit-Queue: Sylvain Defresne <sdefresne@chromium.org>
Cr-Commit-Position: refs/heads/master@{#594721}

components/keyed_service/ios/browser_state_keyed_service_factory.cc

@@ -28,17 +28,15 @@ void BrowserStateKeyedServiceFactory::SetTestingFactory(
 KeyedService* BrowserStateKeyedServiceFactory::SetTestingFactoryAndUse(
     web::BrowserState* context,
     TestingFactory testing_factory) {
-  KeyedServiceFactory::TestingFactory wrapped_factory;
-  if (testing_factory) {
-    wrapped_factory = base::BindRepeating(
-        [](const TestingFactory& testing_factory,
-           base::SupportsUserData* context) {
-          return testing_factory.Run(static_cast<web::BrowserState*>(context));
-        },
-        std::move(testing_factory));
-  }
+  DCHECK(testing_factory);
   return KeyedServiceFactory::SetTestingFactoryAndUse(
-      context, std::move(wrapped_factory));
+      context, base::BindRepeating(
+                   [](const TestingFactory& testing_factory,
+                      base::SupportsUserData* context) {
+                     return testing_factory.Run(
+                         static_cast<web::BrowserState*>(context));
+                   },
+                   std::move(testing_factory)));
 }
 
 BrowserStateKeyedServiceFactory::BrowserStateKeyedServiceFactory(

components/keyed_service/ios/refcounted_browser_state_keyed_service_factory.cc

@@ -30,17 +30,15 @@ scoped_refptr<RefcountedKeyedService>
 RefcountedBrowserStateKeyedServiceFactory::SetTestingFactoryAndUse(
     web::BrowserState* context,
     TestingFactory testing_factory) {
-  RefcountedKeyedServiceFactory::TestingFactory wrapped_factory;
-  if (testing_factory) {
-    wrapped_factory = base::BindRepeating(
-        [](const TestingFactory& testing_factory,
-           base::SupportsUserData* context) {
-          return testing_factory.Run(static_cast<web::BrowserState*>(context));
-        },
-        std::move(testing_factory));
-  }
+  DCHECK(testing_factory);
   return RefcountedKeyedServiceFactory::SetTestingFactoryAndUse(
-      context, std::move(wrapped_factory));
+      context, base::BindRepeating(
+                   [](const TestingFactory& testing_factory,
+                      base::SupportsUserData* context) {
+                     return testing_factory.Run(
+                         static_cast<web::BrowserState*>(context));
+                   },
+                   std::move(testing_factory)));
 }
 
 RefcountedBrowserStateKeyedServiceFactory::