Use the loading task runner for mojo-loading

content/child/resource_dispatcher.cc

 // Copyright (c) 2012 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.
 
 // See http://dev.chromium.org/developers/design-documents/multi-process-resource-loading
 
 #include "content/child/resource_dispatcher.h"
 
 #include <utility>
 
@@ skipping 650 matching lines @@
   pending_requests_[request_id] = base::MakeUnique<PendingRequestInfo>(
       std::move(peer), request->resource_type, request->origin_pid,
       frame_origin, request->url, request->download_to_file);
 
   if (resource_scheduling_filter_.get() && loading_task_runner) {
     resource_scheduling_filter_->SetRequestIdTaskRunner(request_id,
                                                         loading_task_runner);
   }
 
   if (ipc_type == blink::WebURLRequest::LoadingIPCType::Mojo) {
+    scoped_refptr<base::SingleThreadTaskRunner> task_runner =
+        loading_task_runner ? loading_task_runner : main_thread_task_runner_;
     std::unique_ptr<URLLoaderClientImpl> client(
-        new URLLoaderClientImpl(request_id, this, main_thread_task_runner_));
+        new URLLoaderClientImpl(request_id, this, std::move(task_runner)));
     mojom::URLLoaderAssociatedPtr url_loader;
     mojom::URLLoaderClientAssociatedPtrInfo client_ptr_info;
     client->Bind(&client_ptr_info);
     url_loader_factory->CreateLoaderAndStart(MakeRequest(&url_loader),
                                              routing_id, request_id, *request,
                                              std::move(client_ptr_info));
     pending_requests_[request_id]->url_loader = std::move(url_loader);
     pending_requests_[request_id]->url_loader_client = std::move(client);
   } else {
     message_sender_->Send(
@@ skipping 137 matching lines @@
     delete message;
   }
 }
 
 void ResourceDispatcher::SetResourceSchedulingFilter(
     scoped_refptr<ResourceSchedulingFilter> resource_scheduling_filter) {
   resource_scheduling_filter_ = resource_scheduling_filter;
 }
 
 }  // namespace content