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

chrome/browser/download/download_manager.h

 // Copyright (c) 2011 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.
 //
 // The DownloadManager object manages the process of downloading, including
 // updates to the history system and providing the information for displaying
 // the downloads view in the Destinations tab. There is one DownloadManager per
 // active profile in Chrome.
 //
 // Download observers:
@@ skipping 186 matching lines @@
   // Display a new download in the appropriate browser UI.
   void ShowDownloadInBrowser(DownloadItem* download);
 
   // The number of in progress (including paused) downloads.
   int in_progress_count() const {
     return static_cast<int>(in_progress_.size());
   }
 
   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.
   void CreateDownloadItem(DownloadCreateInfo* info);
 
   // Clears the last download path, used to initialize "save as" dialogs.
   void ClearLastDownloadPath();
 
   // Tests if a file type should be opened automatically.
   bool ShouldOpenFileBasedOnExtension(const FilePath& path) const;
@@ skipping 11 matching lines @@
   // Returns true if this download should show the "dangerous file" warning.
   // Various factors are considered, such as the type of the file, whether a
   // user action initiated the download, and whether the user has explicitly
   // marked the file type as "auto open".
   bool IsDangerous(const DownloadItem& download,
                    const DownloadStateInfo& state);
 
   // 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);
 
  private:
   // For testing.
   friend class DownloadManagerTest;
   friend class MockDownloadManager;
 
   // This class is used to let an incognito DownloadManager observe changes to
@@ skipping 154 matching lines @@
   // The "Save As" dialog box used to ask the user where a file should be
   // saved.
   scoped_refptr<SelectFileDialog> select_file_dialog_;
 
   scoped_ptr<OtherDownloadManagerObserver> other_download_manager_observer_;
 
   DISALLOW_COPY_AND_ASSIGN(DownloadManager);
 };
 
 #endif  // CHROME_BROWSER_DOWNLOAD_DOWNLOAD_MANAGER_H_