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

chrome/browser/download/download_manager.h

Index: chrome/browser/download/download_manager.h
diff --git a/chrome/browser/download/download_manager.h b/chrome/browser/download/download_manager.h
index 84b83990bdc9d8b103e2cf6de26f95b2a6239305..13207ac68ba4e29441f3c238e2ae8bb3c3046941 100644
--- a/chrome/browser/download/download_manager.h
+++ b/chrome/browser/download/download_manager.h
@@ -70,6 +70,8 @@ class DownloadManager
  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();
 
@@ -233,6 +235,11 @@ class DownloadManager
   // 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);