Revert of Use the loading task runner for mojo-loading

content/child/resource_dispatcher.cc

Index: content/child/resource_dispatcher.cc
diff --git a/content/child/resource_dispatcher.cc b/content/child/resource_dispatcher.cc
index 04759bbe674cb12b9965bd6616a16b074732af80..2a52bbd100b83485376fc37ea1e405dd07498b29 100644
--- a/content/child/resource_dispatcher.cc
+++ b/content/child/resource_dispatcher.cc
@@ -668,10 +668,8 @@
   }
 
   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, std::move(task_runner)));
+        new URLLoaderClientImpl(request_id, this, main_thread_task_runner_));
     mojom::URLLoaderAssociatedPtr url_loader;
     mojom::URLLoaderClientAssociatedPtrInfo client_ptr_info;
     client->Bind(&client_ptr_info);