Enable use_once_callback for //content/common/*.mojom

content/network/network_service_url_loader_factory_impl.h

 // Copyright 2017 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_NETWORK_NETWORK_SERVICE_URL_LOADER_FACTORY_IMPL_H_
 #define CONTENT_NETWORK_NETWORK_SERVICE_URL_LOADER_FACTORY_IMPL_H_
 
 #include "base/macros.h"
 #include "content/common/url_loader_factory.mojom.h"
 
@@ skipping 13 matching lines @@
   // mojom::URLLoaderFactory implementation.
   void CreateLoaderAndStart(mojom::URLLoaderAssociatedRequest request,
                             int32_t routing_id,
                             int32_t request_id,
                             uint32_t options,
                             const ResourceRequest& url_request,
                             mojom::URLLoaderClientPtr client) override;
   void SyncLoad(int32_t routing_id,
                 int32_t request_id,
                 const ResourceRequest& request,
-                const SyncLoadCallback& callback) override;
+                SyncLoadCallback callback) override;
 
  private:
   // Not owned.
   NetworkContext* context_;
 
   DISALLOW_COPY_AND_ASSIGN(NetworkServiceURLLoaderFactoryImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_NETWORK_NETWORK_SERVICE_URL_LOADER_FACTORY_IMPL_H_