[SyncFS] Add completion callback to PromoteDemotedChanges (1/3)

chrome/browser/sync_file_system/drive_backend/fake_sync_worker.cc

 // Copyright 2014 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 "chrome/browser/sync_file_system/drive_backend/fake_sync_worker.h"
 
 #include "base/values.h"
 #include "chrome/browser/sync_file_system/drive_backend/drive_backend_constants.h"
 #include "chrome/browser/sync_file_system/drive_backend/sync_engine_context.h"
 #include "chrome/browser/sync_file_system/sync_status_code.h"
@@ skipping 112 matching lines @@
 void FakeSyncWorker::SetSyncEnabled(bool enabled) {
   DCHECK(sequence_checker_.CalledOnValidSequencedThread());
   sync_enabled_ = enabled;
 
   if (enabled)
     UpdateServiceState(REMOTE_SERVICE_OK, "Set FakeSyncWorker enabled.");
   else
     UpdateServiceState(REMOTE_SERVICE_DISABLED, "Disabled FakeSyncWorker.");
 }
 
-void FakeSyncWorker::PromoteDemotedChanges() {
+void FakeSyncWorker::PromoteDemotedChanges(const base::Closure& callback) {
   DCHECK(sequence_checker_.CalledOnValidSequencedThread());
   FOR_EACH_OBSERVER(
       Observer,
       observers_,
       OnPendingFileListUpdated(10));
+  callback.Run();
 }
 
 void FakeSyncWorker::ApplyLocalChange(
     const FileChange& local_change,
     const base::FilePath& local_path,
     const SyncFileMetadata& local_metadata,
     const fileapi::FileSystemURL& url,
     const SyncStatusCallback& callback) {
   DCHECK(sequence_checker_.CalledOnValidSequencedThread());
   callback.Run(SYNC_STATUS_OK);
@@ skipping 47 matching lines @@
                                         const std::string& description) {
   DCHECK(sequence_checker_.CalledOnValidSequencedThread());
 
   FOR_EACH_OBSERVER(
       Observer, observers_,
       UpdateServiceState(state, description));
 }
 
 }  // namespace drive_backend
 }  // namespace sync_file_system