[SyncFS] Make GetOriginStatusMap asynchronous

chrome/browser/sync_file_system/drive_backend_v1/drive_file_sync_service.cc

Index: chrome/browser/sync_file_system/drive_backend_v1/drive_file_sync_service.cc
diff --git a/chrome/browser/sync_file_system/drive_backend_v1/drive_file_sync_service.cc b/chrome/browser/sync_file_system/drive_backend_v1/drive_file_sync_service.cc
index fb28520debd5519da0eb94f1b97309f7e58d0beb..950e9f8b47b1e9a2440efb90d1cecc576ee05b60 100644
--- a/chrome/browser/sync_file_system/drive_backend_v1/drive_file_sync_service.cc
+++ b/chrome/browser/sync_file_system/drive_backend_v1/drive_file_sync_service.cc
@@ -229,26 +229,29 @@ RemoteServiceState DriveFileSyncService::GetCurrentState() const {
   return state_;
 }
 
-void DriveFileSyncService::GetOriginStatusMap(OriginStatusMap* status_map) {
-  DCHECK(status_map);
+void DriveFileSyncService::GetOriginStatusMap(
+    const StatusMapCallback& callback) {
+  OriginStatusMap status_map;
 
   // Add batch sync origins held by DriveFileSyncService.
-  typedef std::map<GURL, std::string>::const_iterator iterator;
+  typedef OriginStatusMap::const_iterator iterator;
   for (iterator itr = pending_batch_sync_origins_.begin();
        itr != pending_batch_sync_origins_.end();
        ++itr)
-    (*status_map)[itr->first] = "Pending";
+    status_map[itr->first] = "Pending";
 
   // Add incremental and disabled origins held by DriveMetadataStore.
   for (iterator itr = metadata_store_->incremental_sync_origins().begin();
        itr != metadata_store_->incremental_sync_origins().end();
        ++itr)
-    (*status_map)[itr->first] = "Enabled";
+    status_map[itr->first] = "Enabled";
 
   for (iterator itr = metadata_store_->disabled_origins().begin();
        itr != metadata_store_->disabled_origins().end();
        ++itr)
-    (*status_map)[itr->first] = "Disabled";
+    status_map[itr->first] = "Disabled";
+
+  callback.Run(status_map);
 }
 
 void DriveFileSyncService::DumpFiles(const GURL& origin,