DownloadManager : Create transient downloads

content/browser/download/download_create_info.h

Index: content/browser/download/download_create_info.h
diff --git a/content/browser/download/download_create_info.h b/content/browser/download/download_create_info.h
index f5c11ea0a23e5b749fd27edaed9dd04c03ee53b1..db0620b3fa263d3b785020dc3c09122fa43aca4e 100644
--- a/content/browser/download/download_create_info.h
+++ b/content/browser/download/download_create_info.h
@@ -76,6 +76,10 @@ struct CONTENT_EXPORT DownloadCreateInfo {
   // True if the download was initiated by user action.
   bool has_user_gesture;
 
+  // Whether the download should be transient. A transient download is
+  // short-lived and is not shown in the UI.
+  bool transient;
+
   base::Optional<ui::PageTransition> transition_type;
 
   // The remote IP address where the download was fetched from.  Copied from