downloads: add the ability to undo download removal.

chrome/browser/ui/webui/downloads_dom_handler.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.
 
 #ifndef CHROME_BROWSER_UI_WEBUI_DOWNLOADS_DOM_HANDLER_H_
 #define CHROME_BROWSER_UI_WEBUI_DOWNLOADS_DOM_HANDLER_H_
 
 #include <set>
 #include <vector>
 
@@ skipping 60 matching lines @@
   // Callback for the "pause" message - pauses the file download.
   void HandlePause(const base::ListValue* args);
 
   // Callback for the "resume" message - resumes the file download.
   void HandleResume(const base::ListValue* args);
 
   // Callback for the "remove" message - removes the file download from shelf
   // and list.
   void HandleRemove(const base::ListValue* args);
 
+  // Callback for the "undo" message. Currently only undoes removals.
+  void HandleUndo(const base::ListValue* args);
+
   // Callback for the "cancel" message - cancels the download.
   void HandleCancel(const base::ListValue* args);
 
   // Callback for the "clearAll" message - clears all the downloads.
   void HandleClearAll(const base::ListValue* args);
 
   // Callback for the "openDownloadsFolder" message - opens the downloads
   // folder.
   void HandleOpenDownloadsFolder(const base::ListValue* args);
 
@@ skipping 29 matching lines @@
   // DownloadItem.
   void DangerPromptDone(int download_id, DownloadDangerPrompt::Action action);
 
   // Returns true if the records of any downloaded items are allowed (and able)
   // to be deleted.
   bool IsDeletingHistoryAllowed();
 
   // Returns the download that is referred to in a given value.
   content::DownloadItem* GetDownloadByValue(const base::ListValue* args);
 
+  // Returns the download with |id| or NULL if it doesn't exist.
+  content::DownloadItem* GetDownloadById(uint32 id);
+
   // Current search terms.
   scoped_ptr<base::ListValue> search_terms_;
 
   // Notifies OnDownload*() and provides safe access to the DownloadManager.
   AllDownloadItemNotifier main_notifier_;
 
   // If |main_notifier_| observes an incognito profile, then this observes the
   // DownloadManager for the original profile; otherwise, this is NULL.
   scoped_ptr<AllDownloadItemNotifier> original_notifier_;
 
+  // IDs of downloads to remove when this handler gets deleted.
+  std::vector<uint32> removed_ids_;
+
   // Whether a call to SendCurrentDownloads() is currently scheduled.
   bool update_scheduled_;
 
   base::WeakPtrFactory<DownloadsDOMHandler> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(DownloadsDOMHandler);
 };
 
 #endif  // CHROME_BROWSER_UI_WEBUI_DOWNLOADS_DOM_HANDLER_H_