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 215 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);
 
+  // Checks whether downloaded files still exist. 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.
+  void CheckForFilesRemovalOnFileThread(int64 db_handle, const FilePath& path);
+
+  // 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(int64 db_handle, bool file_exists);
+
   // 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_