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

chrome/browser/sync_file_system/local/local_file_sync_service.cc

 // Copyright 2013 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/local/local_file_sync_service.h"
 
 #include "base/single_thread_task_runner.h"
 #include "base/stl_util.h"
 #include "base/thread_task_runner_handle.h"
 #include "chrome/browser/extensions/extension_util.h"
@@ skipping 24 matching lines @@
 namespace {
 
 void PrepareForProcessRemoteChangeCallbackAdapter(
     const RemoteChangeProcessor::PrepareChangeCallback& callback,
     SyncStatusCode status,
     const LocalFileSyncInfo& sync_file_info,
     webkit_blob::ScopedFile snapshot) {
   callback.Run(status, sync_file_info.metadata, sync_file_info.changes);
 }
 
+void InvokeCallbackOnNthInvocation(int* count, const base::Closure& callback) {
+  --*count;
+  if (*count <= 0)
+    callback.Run();
+}
+
 }  // namespace
 
 LocalFileSyncService::OriginChangeMap::OriginChangeMap()
     : next_(change_count_map_.end()) {}
 LocalFileSyncService::OriginChangeMap::~OriginChangeMap() {}
 
 bool LocalFileSyncService::OriginChangeMap::NextOriginToProcess(GURL* origin) {
   DCHECK(origin);
   if (change_count_map_.empty())
     return false;
@@ skipping 124 matching lines @@
   if (!ContainsKey(origin_to_contexts_, url.origin())) {
     base::ThreadTaskRunnerHandle::Get()->PostTask(
         FROM_HERE,
         base::Bind(callback, SYNC_FILE_ERROR_INVALID_URL, false));
     return;
   }
   sync_context_->HasPendingLocalChanges(
       origin_to_contexts_[url.origin()], url, callback);
 }
 
-void LocalFileSyncService::PromoteDemotedChanges() {
+void LocalFileSyncService::PromoteDemotedChanges(
+    const base::Closure& callback) {
+  if (origin_to_contexts_.empty()) {
+    callback.Run();
+    return;
+  }
+
+  base::Closure completion_callback =
+      base::Bind(&InvokeCallbackOnNthInvocation,
+                 base::Owned(new int(origin_to_contexts_.size())), callback);
   for (OriginToContext::iterator iter = origin_to_contexts_.begin();
        iter != origin_to_contexts_.end(); ++iter)
-    sync_context_->PromoteDemotedChanges(iter->first, iter->second);
+    sync_context_->PromoteDemotedChanges(iter->first, iter->second,
+                                         completion_callback);
 }
 
 void LocalFileSyncService::GetLocalFileMetadata(
     const FileSystemURL& url, const SyncFileMetadataCallback& callback) {
   DCHECK(ContainsKey(origin_to_contexts_, url.origin()));
   sync_context_->GetFileMetadata(origin_to_contexts_[url.origin()],
                                  url, callback);
 }
 
 void LocalFileSyncService::PrepareForProcessRemoteChange(
@@ skipping 281 matching lines @@
 
 LocalChangeProcessor* LocalFileSyncService::GetLocalChangeProcessor(
     const FileSystemURL& url) {
   if (!get_local_change_processor_.is_null())
     return get_local_change_processor_.Run(url.origin());
   DCHECK(local_change_processor_);
   return local_change_processor_;
 }
 
 }  // namespace sync_file_system