For downloads requiring a user gesture, also require...

chrome/browser/download/download_manager.h

Index: chrome/browser/download/download_manager.h
===================================================================
--- chrome/browser/download/download_manager.h	(revision 86341)
+++ chrome/browser/download/download_manager.h	(working copy)
@@ -204,8 +204,6 @@
 
   Profile* profile() { return profile_; }
 
-  DownloadHistory* download_history() { return download_history_.get(); }
-
   DownloadPrefs* download_prefs() { return download_prefs_.get(); }
 
   // Creates the download item.  Must be called on the UI thread.
@@ -237,9 +235,17 @@
   // Called when the user has validated the download of a dangerous file.
   void DangerousDownloadValidated(DownloadItem* download);
 
+  // Callback function after we check whether the referrer URL has been visited
+  // before today.
+  void CheckVisitedBeforeDone(int32 download_id, bool visited_before);

[Randy Smith (Not in Mondays), 2011/05/24 18:28:25]

I don't understand the meaning of |visited_before| (either here or looking at
the code) which suggests that it needs a better comment.

[Peter Kasting, 2011/05/24 20:55:00]

I added the word "referrer" to the function and argument names.  See if that
helps.

+
   // Callback function after url is checked with safebrowsing service.
   void CheckDownloadUrlDone(int32 download_id, bool is_dangerous_url);
 
+  // Called by both the above CheckXXX() functions, proceeds once both checks
+  // have completed.
+  void HistoryAndSBChecksMaybeDone(DownloadItem* download);
+
   // Callback function after download file hash is checked with safebrowsing
   // service.
   void CheckDownloadHashDone(int32 download_id, bool is_dangerous_hash);