Reduce/remove usage of BrowserThread in content/browser/loader.

content/browser/loader/url_loader_factory_impl.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 CONTENT_BROWSER_LOADER_URL_LOADER_FACTORY_IMPL_H_
 #define CONTENT_BROWSER_LOADER_URL_LOADER_FACTORY_IMPL_H_
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
+#include "base/single_thread_task_runner.h"
 #include "content/common/content_export.h"
 #include "content/common/url_loader_factory.mojom.h"
 
 namespace content {
 
 class ResourceRequesterInfo;
 
 // This class is an implementation of mojom::URLLoaderFactory that creates
 // a mojom::URLLoader. This class is instantiated only for Service Worker
 // navigation preload or test caseses.
@@ skipping 20 matching lines @@
   static void SyncLoad(ResourceRequesterInfo* requester_info,
                        int32_t routing_id,
                        int32_t request_id,
                        const ResourceRequest& request,
                        const SyncLoadCallback& callback);
 
   // Creates a URLLoaderFactoryImpl instance. The instance is held by the
   // StrongBinding in it, so this function doesn't return the instance.
   CONTENT_EXPORT static void Create(
       scoped_refptr<ResourceRequesterInfo> requester_info,
-      mojom::URLLoaderFactoryRequest request);
+      mojom::URLLoaderFactoryRequest request,
+      const scoped_refptr<base::SingleThreadTaskRunner>& io_thread_runner);
 
  private:
   explicit URLLoaderFactoryImpl(
-      scoped_refptr<ResourceRequesterInfo> requester_info);
+      scoped_refptr<ResourceRequesterInfo> requester_info,
+      const scoped_refptr<base::SingleThreadTaskRunner>& io_thread_runner);
 
   scoped_refptr<ResourceRequesterInfo> requester_info_;
 
+  // Task runner for the IO thead.
+  scoped_refptr<base::SingleThreadTaskRunner> io_thread_task_runner_;
+
   DISALLOW_COPY_AND_ASSIGN(URLLoaderFactoryImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_LOADER_URL_LOADER_FACTORY_IMPL_H_