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

chrome/browser/ui/webui/downloads_dom_handler.cc

Index: chrome/browser/ui/webui/downloads_dom_handler.cc
diff --git a/chrome/browser/ui/webui/downloads_dom_handler.cc b/chrome/browser/ui/webui/downloads_dom_handler.cc
index 75209330acf6281ba5b485dfafc317ea080ddd0d..18c04a5e036ef96570f269f5858d5ee1e47405f1 100644
--- a/chrome/browser/ui/webui/downloads_dom_handler.cc
+++ b/chrome/browser/ui/webui/downloads_dom_handler.cc
@@ -124,15 +124,6 @@ void DownloadsDOMHandler::ModelChanged() {
        it != download_items_.end(); ++it) {
     if (static_cast<int>(it - download_items_.begin()) > kMaxDownloads)
       break;
-
-    DownloadItem* download = *it;
-    if (download->IsInProgress()) {
-      // We want to know what happens as the download progresses.
-      download->AddObserver(this);
-    } else if (download->safety_state() == DownloadItem::DANGEROUS) {
-      // We need to be notified when the user validates the dangerous download.
-      download->AddObserver(this);
-    }
   }
 
   SendCurrentDownloads();
@@ -146,6 +137,8 @@ void DownloadsDOMHandler::HandleGetDownloads(const ListValue* args) {
   } else {
     SendCurrentDownloads();
   }
+
+  download_manager_->CheckForFilesRemoval();
 }
 
 void DownloadsDOMHandler::HandleOpenFile(const ListValue* args) {
@@ -211,6 +204,9 @@ void DownloadsDOMHandler::SendCurrentDownloads() {
   ListValue results_value;
   for (OrderedDownloads::iterator it = download_items_.begin();
       it != download_items_.end(); ++it) {
+    // Add observers for all download items just once
+    if (!(*it)->HasObserver(this))
+      (*it)->AddObserver(this);
     int index = static_cast<int>(it - download_items_.begin());
     if (index > kMaxDownloads)
       break;