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;

[Paweł Hajdan Jr., 2011/05/10 11:37:51]

nit: According to
http://google-styleguide.googlecode.com/svn/trunk/cppguide.xml?showone=Declar...,
typedefs should be listed before ctors. Sorry I missed that earlier.

+
   // 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 the existence of downloaded files.

[Paweł Hajdan Jr., 2011/05/10 11:37:51]

The comment should be more precise than "Check". It's not necessarily obvious
what that means. How about "Checks whether downloaded files still exists.
Updates state of downloads that refer to removed files. The check runs in the
background and may finish asynchronously after this method returns."?

+  void CheckForFilesRemoval();
+
   // 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 19 matching lines @@
     // The original profile's download manager.
     DownloadManager* observed_download_manager_;
   };
 
   friend struct BrowserThread::DeleteOnThread<BrowserThread::UI>;
   friend class DeleteTask<DownloadManager>;
   friend class OtherDownloadManagerObserver;
 
   ~DownloadManager();
 
+  // Called on the FILE thread to check the existence of downloaded files.
+  // We don't check the file existence on the UI thread to prevent UI thread

[Paweł Hajdan Jr., 2011/05/10 11:37:51]

nit: Remove the "We don't" part, we don't write that in every place using the
FILE thread.

+  // from stalling by interacting with the file system.
+  void CheckForFilesRemovalOnFileThread(const PathVector& existing_paths);

[Paweł Hajdan Jr., 2011/05/10 11:37:51]

nit: How about renaming existing_paths to just paths? They are not necessarily
existing, we have to check for that.

+
+  // Called on the UI thread when the FILE thread finishes to check the
+  // existence of downloaded files. The UI thread updates the state of the
+  // downloaded but non-existent files, and then notifies the fact to the
+  // observers of those files.
+  void OnFilesRemovalDetected(const PathVector& removed_paths);
+
   // Called on the download thread to check whether the suggested file path
   // exists.  We don't check if the file exists on the UI thread to avoid UI
   // stalls from interacting with the file system.
   void CheckIfSuggestedPathExists(DownloadCreateInfo* info,
                                   const FilePath& default_path);
 
   // Called on the UI thread once the DownloadManager has determined whether the
   // suggested file path exists.
   void OnPathExistenceAvailable(DownloadCreateInfo* info);
 
@@ skipping 108 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_