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

chrome/browser/download/download_util.cc

 // 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.
 //
 // Download utility implementation
 
 #include "chrome/browser/download/download_util.h"
 
 #if defined(OS_WIN)
 #include <shobjidl.h>
@@ skipping 646 matching lines @@
     file_value->SetInteger("percent",
         static_cast<int>(download->PercentComplete()));
     file_value->SetInteger("received",
         static_cast<int>(download->received_bytes()));
   } else if (download->IsCancelled()) {
     file_value->SetString("state", "CANCELLED");
   } else if (download->IsComplete()) {
     if (download->safety_state() == DownloadItem::DANGEROUS) {
       file_value->SetString("state", "DANGEROUS");
     } else {
-      file_value->SetString("state", "COMPLETE");
+      bool path_exists = true;
+#if defined(OS_WIN)
+      if (GetFileAttributes(
+              download->GetTargetFilePath().value().c_str()) ==
+          INVALID_FILE_ATTRIBUTES)
+        path_exists = false;
+#elif defined(OS_POSIX)
+      if (access(download->GetTargetFilePath().value().c_str(), F_OK) != 0)
+        path_exists = false;
+#else
+      NOTIMPLEMENTED();
+#endif
+      file_value->SetString("state", path_exists ? "COMPLETE" : "REMOVED");

[Randy Smith (Not in Mondays), 2011/04/27 18:21:21]

All file system accesses need to happen on the FILE thread. 
CreateDownloadItemValue isn't restricted to the file thread, and I believe (from
a cursory scan of the call sites) is usually called on the UI thread.  So this
won't work.

[Paweł Hajdan Jr., 2011/04/29 08:43:41]

Exactly. And using SetAllow... or re-implementing the code is really just
bypassing checks intended to catch blocking IO on wrong threads.

Please note we also cannot jump through the FILE thread in a way that would make
the UI thread block or wait on the FILE thread.

I think the check for file existence should be done asynchronously.

     }
   }
 
   file_value->SetInteger("total",
       static_cast<int>(download->total_bytes()));
 
   return file_value;
 }
 
 string16 GetProgressStatusText(DownloadItem* download) {
@@ skipping 212 matching lines @@
     // Extensions that are not from the gallery are considered dangerous.
     ExtensionService* service = profile->GetExtensionService();
     if (!service ||
         !service->IsDownloadFromGallery(info->url(), info->referrer_url))
       return true;
   }
   return false;
 }
 
 }  // namespace download_util