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

chrome/browser/sync_file_system/drive_backend/drive_backend_sync_unittest.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 <algorithm>
 #include <stack>
 
 #include "base/file_util.h"
 #include "base/message_loop/message_loop.h"
 #include "base/run_loop.h"
@@ skipping 338 matching lines @@
         return local_sync_status;
 
       remote_sync_status = ProcessRemoteChange();
       if (remote_sync_status != SYNC_STATUS_OK &&
           remote_sync_status != SYNC_STATUS_NO_CHANGE_TO_SYNC &&
           remote_sync_status != SYNC_STATUS_FILE_BUSY)
         return remote_sync_status;
 
       if (local_sync_status == SYNC_STATUS_NO_CHANGE_TO_SYNC &&
           remote_sync_status == SYNC_STATUS_NO_CHANGE_TO_SYNC) {
-        remote_sync_service_->PromoteDemotedChanges();
-        local_sync_service_->PromoteDemotedChanges();
+
+        {
+          base::RunLoop run_loop;
+          remote_sync_service_->PromoteDemotedChanges(run_loop.QuitClosure());
+          run_loop.Run();
+        }
+
+        {
+          base::RunLoop run_loop;
+          local_sync_service_->PromoteDemotedChanges(run_loop.QuitClosure());
+          run_loop.Run();
+        }
 
         if (pending_remote_changes_ || pending_local_changes_)
           continue;
 
         base::RunLoop run_loop;
         int64 largest_fetched_change_id = -1;
         PostTaskAndReplyWithResult(
             worker_task_runner_,
             FROM_HERE,
             base::Bind(&MetadataDatabase::GetLargestFetchedChangeID,
@@ skipping 1325 matching lines @@
 
   EXPECT_EQ(1u, CountApp());
   EXPECT_EQ(1u, CountLocalFile(app_id));
 
   EXPECT_EQ(2u, CountMetadata());
   EXPECT_EQ(2u, CountTracker());
 }
 
 }  // namespace drive_backend
 }  // namespace sync_file_system