downloads: add the ability to undo download removal.

chrome/browser/download/all_download_item_notifier.cc

Index: chrome/browser/download/all_download_item_notifier.cc
diff --git a/chrome/browser/download/all_download_item_notifier.cc b/chrome/browser/download/all_download_item_notifier.cc
index a0b3a02eff5b863d69f114a779f57b962bdfa5d3..c69380ea24aa4697162e2b4b7113bf2f766ce05c 100644
--- a/chrome/browser/download/all_download_item_notifier.cc
+++ b/chrome/browser/download/all_download_item_notifier.cc
@@ -47,6 +47,12 @@ void AllDownloadItemNotifier::OnDownloadCreated(
   observer_->OnDownloadCreated(manager, item);
 }
 
+void AllDownloadItemNotifier::OnDownloadRevived(
+    content::DownloadManager* manager,
+    content::DownloadItem* item) {
+  observer_->OnDownloadRevived(manager, item);
+}
+
 void AllDownloadItemNotifier::OnDownloadUpdated(
     content::DownloadItem* item) {
   observer_->OnDownloadUpdated(manager_, item);