[ObjC ARC] Converts ios/web/public/test/fakes:fakes to ARC.

ios/web/public/test/fakes/test_web_state_delegate.mm

Index: ios/web/public/test/fakes/test_web_state_delegate.mm
diff --git a/ios/web/public/test/fakes/test_web_state_delegate.mm b/ios/web/public/test/fakes/test_web_state_delegate.mm
index 23f18c458ea1cf70642372caa74f747987e97ee6..4e545326bf199cd7349c74280d847678cc7d10ea 100644
--- a/ios/web/public/test/fakes/test_web_state_delegate.mm
+++ b/ios/web/public/test/fakes/test_web_state_delegate.mm
@@ -6,6 +6,10 @@
 
 #include "base/memory/ptr_util.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 namespace web {
 
 TestOpenURLRequest::TestOpenURLRequest()
@@ -118,9 +122,8 @@ void TestWebStateDelegate::OnAuthRequired(
     const AuthCallback& callback) {
   last_authentication_request_ = base::MakeUnique<TestAuthenticationRequest>();
   last_authentication_request_->web_state = source;
-  last_authentication_request_->protection_space.reset(
-      [protection_space retain]);
-  last_authentication_request_->credential.reset([credential retain]);
+  last_authentication_request_->protection_space = protection_space;
+  last_authentication_request_->credential = credential;
   last_authentication_request_->auth_callback = callback;
 }