DownloadManager::Observer::OnDownloadCreated

content/public/browser/download_manager.h

 // Copyright (c) 2012 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 browser context in Chrome.
 //
 // Download observers:
@@ skipping 61 matching lines @@
   // Shutdown the download manager. Content calls this when BrowserContext is
   // being destructed. If the embedder needs this to be called earlier, it can
   // call it. In that case, the delegate's Shutdown() method will only be called
   // once.
   virtual void Shutdown() = 0;
 
   // Interface to implement for observers that wish to be informed of changes
   // to the DownloadManager's collection of downloads.
   class CONTENT_EXPORT Observer {
    public:
+    // A DownloadItem was created.  Unlike ModelChanged, this item may be
+    // visible before the filename is determined; in this case the return value
+    // of GetTargetFileName() will be null.  This method may be called an
+    // arbitrary number of times, e.g. when loading history on startup.  As a
+    // result, consumers should avoid doing large amounts of work in
+    // OnDownloadCreated().  TODO(<whoever>): When we've fully specified the
+    // possible states of the DownloadItem in download_item.h and removed
+    // ModelChanged, we should remove the caveat above.
+    virtual void OnDownloadCreated(
+        DownloadManager* manager, DownloadItem* item) {}
+
     // New or deleted download, observers should query us for the current set
     // of downloads.
-    virtual void ModelChanged(DownloadManager* manager) = 0;
+    virtual void ModelChanged(DownloadManager* manager) {}
 
     // Called when the DownloadManager is being destroyed to prevent Observers
     // from calling back to a stale pointer.
     virtual void ManagerGoingDown(DownloadManager* manager) {}
 
     // Called immediately after the DownloadManager puts up a select file
     // dialog.
     // |id| indicates which download opened the dialog.
     virtual void SelectFileDialogDisplayed(
         DownloadManager* manager, int32 id) {}
@@ skipping 136 matching lines @@
  protected:
   virtual ~DownloadManager() {}
 
  private:
   friend class base::RefCountedThreadSafe<DownloadManager>;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_DOWNLOAD_MANAGER_H_