Create a Delayed Response Provider for GCDWebServer.

ios/web/public/test/response_providers/delayed_response_provider.h

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef IOS_WEB_PUBLIC_TEST_RESPONSE_PROVIDERS_DELAYED_RESPONSE_PROVIDER_H_
+#define IOS_WEB_PUBLIC_TEST_RESPONSE_PROVIDERS_DELAYED_RESPONSE_PROVIDER_H_
+
+#include <memory>
+
+#include "ios/web/public/test/response_providers/response_provider.h"
+
+namespace web {
+
+// A Response provider that delays the response provided by another reponse
+// provider
+class DelayedResponseProvider : public web::ResponseProvider {

[stkhapugin, 2016/08/26 13:06:48]

nit: You are in namespace web, so I guess you can remove web::

[Olivier, 2016/08/26 14:10:03]

Done.

+ public:
+  // Designated creator. Will create a DelayedResponseProvider that delays the

[stkhapugin, 2016/08/26 13:06:47]

s/creator/constructor. s/Will create/Creates. 

[Olivier, 2016/08/26 14:10:03]

Done.

+  // response from |delayed_provider| by |delay| seconds.
+  DelayedResponseProvider(
+      std::unique_ptr<web::ResponseProvider> delayed_provider,
+      double delay);
+  ~DelayedResponseProvider() override;
+
+  // Returns true if the request is handled by the |delayed_provider_|.

[stkhapugin, 2016/08/26 13:06:48]

Optional: rephrase it: "Forwards to |delayed_provider_|." here and below. It's
clearer, as this is exactly what you do. 

[Olivier, 2016/08/26 14:10:03]

Done.

+  bool CanHandleRequest(const Request& request) override;
+
+  // Returns the GCDWebServerResponse as a reply to the request. Will only be
+  // called if the |delayed_provider_| can handle the request.
+  GCDWebServerResponse* GetGCDWebServerResponse(
+      const Request& request) override;
+

[stkhapugin, 2016/08/26 13:06:47]

You may want disallow copy and assign

[Olivier, 2016/08/26 14:10:03]

Done.

+ private:
+  std::unique_ptr<web::ResponseProvider> delayed_provider_;
+  double delay_;
+};
+
+}  // namespace web
+
+#endif  // IOS_WEB_PUBLIC_TEST_RESPONSE_PROVIDERS_DELAYED_RESPONSE_PROVIDER_H_