Implement the infrastructure of creating WorkerFetchContext in worker global scope.

content/common/worker_fetch_context_factory.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 "url_loader_factory.mojom";
+
+interface ServiceWorkerClient {
+  // Called when the ServiceWorkerClient (which is Dedicated Worker or Shared

[kinuko, 2017/04/14 14:00:26]

Too generic name if it's only for clients that live on worker threads?

[horo, 2017/04/17 15:12:04]

Done.

+  // Worker) is controlled by a new service worker.
+  SetControllerServiceWorker(int64 controller_version_id);
+};
+
+interface WorkerFetchContextFactory {

[kinuko, 2017/04/14 14:00:26]

Can we also have a interface-level comment?

I'm having slightly uneasy feeling about this interface name (and method names).
 While it's true that this is for FetchContext in Blink context, calling this
WorkerURLLoaderFactoryProvider or something like that may make better sense in
mojo / browser-side context?

[horo, 2017/04/17 15:12:04]

Done.

+  // Called from a dedicated (or shared) worker thread to create a worker fetch
+  // context.
+  // The browser process returns a URLLoaderFactory. SetControllerServiceWorker
+  // method of the passed ServiceWorkerClient interface will be called when the
+  // parent frame and the worker context is controlled by a service worker.
+  // |service_worker_provider_id| is the service worker provider id of the
+  // parent frame.
+  CreateWorkerFetchContext(associated URLLoaderFactory& loader,
+                           associated ServiceWorkerClient client,
+                           int32 service_worker_provider_id);

[kinuko, 2017/04/14 14:00:26]

Similarly, this seems to be more about setting up URLLoaderFactory (as well as
returning a control channel for SW).

[horo, 2017/04/17 15:12:04]

Does 'this' mean GetURLLoaderFactory?
GetURLLoaderFactory is just returning the URLLoaderFactory.

[kinuko, 2017/04/18 08:00:31]

Sorry, I meant 'CreateWorkerFetchContext' one.  This IPC doesn't really create a
worker fetch context, does it?

[horo, 2017/04/18 12:53:33]

This IPC is used to get the URLLoaderFactory and register the worker fetch
context to the service worker context in the browser process.  Can't we say this
is "creating" the worker fetch context?

[kinuko, 2017/04/19 03:24:49]

This IPC is used to get the URLLoaderFactory and register the
ServiceWorkerWorkerClient in the service worker's provider host, that's what I'm
seeing.  WorkerFetchContext seems to be the renderer-side consequence that
doesn't need to be surfaced at this IPC layer... that's my view.  (Apologies for
biked-sheding, naming is hard)

+
+  // Called from the service worker thread to get the URLLoaderFactory.
+  GetURLLoaderFactory(associated URLLoaderFactory& loader);
+};