[Background Sync] Use Mojo IPC to fire background sync events

content/common/background_sync_service.mojom

Index: content/common/background_sync_service.mojom
diff --git a/content/common/background_sync_service.mojom b/content/common/background_sync_service.mojom
index 8321ae9dc7dccaa479d14e538c63500ddedc939d..1ec5fdf9151124e193b0e7a8316b33bc00348cfc 100644
--- a/content/common/background_sync_service.mojom
+++ b/content/common/background_sync_service.mojom
@@ -15,6 +15,13 @@ enum BackgroundSyncError {
   MAX=NO_SERVICE_WORKER
 };
 
+enum BackgroundSyncEventStatus {
+  COMPLETED,
+  REJECTED,
+  ABORT,
+  MAX=ABORT
+};
+
 interface BackgroundSyncService {
   Register(SyncRegistration options, int64 service_worker_registration_id)
       => (BackgroundSyncError err, SyncRegistration options);
@@ -31,7 +38,7 @@ interface BackgroundSyncService {
       => (BackgroundSyncError err, PermissionStatus status);
 };
 
-interface BackgoundSyncServiceClient {
-  Sync(SyncRegistration event);
+interface BackgroundSyncServiceClient {
+  Sync(SyncRegistration event, int32 thread_id) => (BackgroundSyncEventStatus status);
 };