Fix ChangeListLoader's callback invocation.

chrome/browser/chromeos/drive/change_list_loader.h

Index: chrome/browser/chromeos/drive/change_list_loader.h
diff --git a/chrome/browser/chromeos/drive/change_list_loader.h b/chrome/browser/chromeos/drive/change_list_loader.h
index ec867a1336dc37ec57384381907ceba4485b84d9..ac5d2d4ec8be353037cf609b7483f8f1a46f1c0b 100644
--- a/chrome/browser/chromeos/drive/change_list_loader.h
+++ b/chrome/browser/chromeos/drive/change_list_loader.h
@@ -152,8 +152,10 @@ class ChangeListLoader {
       google_apis::GDataErrorCode status,
       scoped_ptr<google_apis::AboutResource> about_resource);
 
-  // Initiates the directory contents loading, based on
-  // |directory_fetch_info|.
+  // Initiates the directory contents loading, based on |directory_fetch_info|.
+  // When it is finished it just runs |callback| but no other callbacks in
+  // |pending_load_callback_|, because it depends on the caller whether to flush
+  // callbacks. Thus, the caller must be responsible for task flushing.
   void DoLoadDirectoryFromServer(const DirectoryFetchInfo& directory_fetch_info,
                                  const FileOperationCallback& callback);