Add two interfaces for ServiceWorkerProviderContext/ProviderHost

content/common/service_worker/service_worker.mojom

 // 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.
 
 module content.mojom;
 
 import "content/common/service_worker/service_worker_provider.mojom";
 
 // Per-process browser-side interface bound to ServiceWorkerDispatcherHost.
 // Each InterfacePtrs on the same render process will be bound to the same
 // ServiceWorkerDispatcherHost.
 interface ServiceWorkerDispatcherHost {
   OnProviderCreated(ServiceWorkerProviderHostInfo provider_info);

[falken, 2017/03/28 06:29:43]

Should we document what balances out OnProviderCreated, now that
OnProviderDestroyed is gone?

[shimazu, 2017/05/08 08:34:29]

Done.

-  OnProviderDestroyed(int32 provider_id);
 
   // Informs the browser that a service worker is starting up. |provider_id|
   // identifies the ServiceWorkerProviderHost hosting the service
   // worker. |version_id| identifies the ServiceWorkerVersion and
   // |embedded_worker_id| identifies the EmbeddedWorkerInstance.  
   OnSetHostedVersionId(int32 provider_id,
                        int64 version_id,
                        int32 embedded_worker_id);
 };