[BackgroundSync] Move BackgroundSyncState from proto to mojo

content/common/background_sync_service.mojom

 // Copyright 2015 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;
 
 import "content/public/common/background_sync.mojom";
 import "content/public/common/permission_status.mojom";
 import "content/public/common/service_worker_event_status.mojom";
 
 enum BackgroundSyncError {
   NONE,
   STORAGE,
   NOT_FOUND,
   NO_SERVICE_WORKER,
   NOT_ALLOWED,
   MAX=NOT_ALLOWED
 };
 
+enum BackgroundSyncState {
+  PENDING,
+  FIRING,
+  FAILED
+ };
+
 interface BackgroundSyncService {
   Register(SyncRegistration options, int64 service_worker_registration_id,
            bool requested_from_service_worker)
       => (BackgroundSyncError err, SyncRegistration options);
   GetRegistration(BackgroundSyncPeriodicity periodicity, string tag,
                   int64 service_worker_registration_id)
       => (BackgroundSyncError err, SyncRegistration? registration);
   GetRegistrations(BackgroundSyncPeriodicity periodicity,
                    int64 service_worker_registration_id)
       => (BackgroundSyncError err, array<SyncRegistration> registrations);
   Unregister(BackgroundSyncPeriodicity periodicity, int32 handle_id,
              int64 service_worker_registration_id) => (BackgroundSyncError err);
   GetPermissionStatus(BackgroundSyncPeriodicity periodicity,
                       int64 service_worker_registration_id)
       => (BackgroundSyncError err, PermissionStatus status);
   DuplicateRegistrationHandle(int32 handle_id) 
       => (BackgroundSyncError err, SyncRegistration? registration);  
   ReleaseRegistration(int32 handle_id);
 };
 
 interface BackgroundSyncServiceClient {
   Sync(int32 handle_id)
       => (ServiceWorkerEventStatus status);
 };