Detect removed files and reflect the state in chrome://downloads and the download shelf

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 52 matching lines @@
 
 // Browser's download manager: manages all downloads and destination view.
 class DownloadManager
     : public base::RefCountedThreadSafe<DownloadManager,
                                         BrowserThread::DeleteOnUIThread>,
       public DownloadStatusUpdaterDelegate,
       public SelectFileDialog::Listener {
  public:
   explicit DownloadManager(DownloadStatusUpdater* status_updater);
 
+  typedef std::vector<std::pair<int64, FilePath> > PathVector;
+
   // Shutdown the download manager. Must be called before destruction.
   void Shutdown();
 
   // Interface to implement for observers that wish to be informed of changes
   // to the DownloadManager's collection of downloads.
   class Observer {
    public:
     // New or deleted download, observers should query us for the current set
     // of downloads.
     virtual void ModelChanged() = 0;
@@ skipping 143 matching lines @@
   virtual int64 GetReceivedDownloadBytes();
   virtual int64 GetTotalDownloadBytes();
 
   // Overridden from SelectFileDialog::Listener:
   virtual void FileSelected(const FilePath& path, int index, void* params);
   virtual void FileSelectionCanceled(void* params);
 
   // Called when the user has validated the download of a dangerous file.
   void DangerousDownloadValidated(DownloadItem* download);
 
+  // Check if the path of each downloaded file still exists or not.
+  void CheckExistingPaths();

[Paweł Hajdan Jr., 2011/05/10 07:59:46]

nit: Would CheckForFilesRemoval (or similar) be a better name?
CheckExistingPaths suggests we do some verification of _existing_ paths, but
here we don't know whether they exist, and we're checking for their existence.

Also, this method not just checks, it updates the state of the downloads item.
And also we do that to display an indication of removed files in the UI. Please
make sure to update the comment.

+  void CheckExistingPathsOnFileThread(PathVector existing_paths);

[Paweł Hajdan Jr., 2011/05/10 07:59:46]

nit: Why not const PathVector&, here and below?

Also, only CheckExistingPaths needs to be public, please make other two methods
private and add comments.

+  void OnExistingPathsAvailable(PathVector removed_paths);
+
   // Callback function after url is checked with safebrowsing service.
   void CheckDownloadUrlDone(DownloadCreateInfo* info, bool is_dangerous_url);
 
   // 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;
@@ skipping 147 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_