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..c2917e07a1a739a4e01915b371eabba02f0ef2c6 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;

[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();
 
@@ -233,6 +235,9 @@ class DownloadManager
   // 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);
 
@@ -272,6 +277,17 @@ class DownloadManager
 
   ~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.