Reland of Add --headless flag to Windows

headless/public/util/testing/generic_url_request_mocks.cc

 // 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.
 
 #include "headless/public/util/testing/generic_url_request_mocks.h"
 
 #include <utility>
 
 #include "base/logging.h"
 #include "base/threading/thread_task_runner_handle.h"
+#include "net/http/http_response_headers.h"
 
 namespace net {
 class URLRequestJob;
 }  // namespace net
 
 namespace headless {
 
 // MockGenericURLRequestJobDelegate
 MockGenericURLRequestJobDelegate::MockGenericURLRequestJobDelegate()
     : main_thread_task_runner_(base::ThreadTaskRunnerHandle::Get()) {}
@@ skipping 155 matching lines @@
                                              int bytes_read) {}
 const std::string& MockURLRequestDelegate::response_data() const {
   return response_data_;
 }
 
 const net::IOBufferWithSize* MockURLRequestDelegate::metadata() const {
   return nullptr;
 }
 
 }  // namespace headless