BackgroundFetchRegistration.abort() should return a Promise.

content/browser/background_fetch/background_fetch_service_impl.cc

 // 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.
 
 #include "content/browser/background_fetch/background_fetch_service_impl.h"
 
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
 #include "content/browser/background_fetch/background_fetch_context.h"
 #include "content/browser/service_worker/service_worker_context_wrapper.h"
@@ skipping 32 matching lines @@
     const UpdateUICallback& callback) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
 
   // TODO(peter): Get the BackgroundFetchJobController for the
   // {service_worker_registration_id, tag} pair and call UpdateUI() on it.
 
   callback.Run(blink::mojom::BackgroundFetchError::NONE);
 }
 
 void BackgroundFetchServiceImpl::Abort(int64_t service_worker_registration_id,
-                                       const std::string& tag) {
+                                       const std::string& tag,
+                                       const AbortCallback& callback) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
 
   // TODO(peter): Get the BackgroundFetchJobController for the
   // {service_worker_registration_id, tag} pair and call Abort() on it.
+
+  callback.Run(blink::mojom::BackgroundFetchError::NONE);
 }
 
 void BackgroundFetchServiceImpl::GetRegistration(
     int64_t service_worker_registration_id,
     const std::string& tag,
     const GetRegistrationCallback& callback) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
 
   // TODO(peter): Get the registration for {service_worker_registration_id, tag}
   // and construct a BackgroundFetchRegistrationPtr for it.
 
   callback.Run(blink::mojom::BackgroundFetchError::NONE,
                nullptr /* registration */);
 }
 
 void BackgroundFetchServiceImpl::GetTags(int64_t service_worker_registration_id,
                                          const GetTagsCallback& callback) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
 
   // TODO(peter): Get the list of active Background Fetches associated with
   // service_worker_registration_id and share their tags.
 
   callback.Run(blink::mojom::BackgroundFetchError::NONE,
                std::vector<std::string>());
 }
 
 }  // namespace content