What steps will reproduce the problem?
(1) Use web::DelayedResponseProvider with an arbitrary web::ResponseProvider;
(2) Send request to web::DelayedResponseProvider and check the result.

What is the expected result?
web::DelayedResponseProvider should return the response of its wrapped web::ResponseProvider.

What happens instead?
The web::DelayedResponseProvider always returns "Slow Page".

Here is the code that produces this bug: https://cs.chromium.org/chromium/src/ios/web/public/test/http_server/delayed_response_provider.mm?rcl=96e64f1e1801c2be586b7fbb206820e374a204c1&l=57