Implement dumb URLLoader{Factory} for ServiceWorker script loading

content/common/service_worker/service_worker_provider.mojom

 // 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.
 
 module content.mojom;
 
 import "content/common/service_worker/service_worker_provider_interfaces.mojom";
 import "content/common/service_worker/service_worker_types.mojom";
+import "content/common/url_loader_factory.mojom";
 
 // A container object carried from the browser to the renderer process.
 // This contains the params for the constructor of ServiceWorkerNetworkProvider.
 // This is passed on launching a service worker.
 struct ServiceWorkerProviderClientInfo {
   int32 provider_id;
   ServiceWorkerProviderType type;
   bool is_parent_frame_secure;
   // |registration| and |attributes| are information about the registration
   // currently to be launched.
   ServiceWorkerRegistrationObjectInfo registration;
   ServiceWorkerVersionAttributes attributes;
 
   associated ServiceWorkerProviderHost host_ptr_info;
   associated ServiceWorkerProvider& client_request;
+  associated URLLoaderFactory script_loader_factory_ptr_info;

[shimazu, 2017/06/16 04:45:07]

Should it be associated with EmbeddedWorkerInstanceClient? 
I assume it's fine to use an isolated pipe because the loader's IPCs are
originally async and other logics don't rely on the order of IPCs.

// I'm not strongly confident of it, so sorry if I missed something!

[kinuko, 2017/06/16 09:15:15]

At some point I think we can make this independent, but for now it seems it'd be
safer to keep ordering with, say, OnScriptLoaded etc?

 };
 
 // A container object carried from the renderer to the browser process.
 // This contains the parameters to specify the provider on the browser side.
 // See also comments in
 // content/common/service_worker/service_worker_provider_host_info.h.
 struct ServiceWorkerProviderHostInfo {
   int32 provider_id;
   int32 route_id;
   ServiceWorkerProviderType type;
   bool is_parent_frame_secure;
   associated ServiceWorkerProviderHost& host_request;
   associated ServiceWorkerProvider client_ptr_info;
-};
+};