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

ios/web/public/test/http_server/delayed_response_provider.mm

 // 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.
 
 #import "ios/web/public/test/http_server/delayed_response_provider.h"
 
 #import <Foundation/Foundation.h>
 
 #include "base/bind.h"
-#import "base/ios/weak_nsobject.h"
 #import "base/mac/foundation_util.h"
-#import "base/mac/scoped_nsobject.h"
 #include "base/memory/ptr_util.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "net/test/embedded_test_server/http_response.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 namespace web {
 
 // Delays |delay| seconds before sending a response to the client.
 class DelayedHttpResponse : public net::test_server::BasicHttpResponse {
  public:
   explicit DelayedHttpResponse(double delay) : delay_(delay) {}
 
   void SendResponse(
       const net::test_server::SendBytesCallback& send,
       const net::test_server::SendCompleteCallback& done) override {
@@ skipping 23 matching lines @@
 
 std::unique_ptr<net::test_server::HttpResponse>
 DelayedResponseProvider::GetEmbeddedTestServerResponse(const Request& request) {
   std::unique_ptr<net::test_server::BasicHttpResponse> http_response(
       base::MakeUnique<DelayedHttpResponse>(delay_));
   http_response->set_content_type("text/html");
   http_response->set_content("Slow Page");
   return std::move(http_response);
 }
 }  // namespace web