Reland DownloadItem::Observer::OnDownloadDestroyed() replaces DownloadItem::REMOVING

chrome/browser/download/download_completion_observer_win.cc

 // Copyright (c) 2012 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.
 
 #include "chrome/browser/download/download_completion_observer_win.h"
 
 #include <string>
 
 #include "base/logging.h"
 #include "base/stl_util.h"
@@ skipping 65 matching lines @@
                                L"",
                                notification_id.c_str());
         }
       }
       DCHECK(ContainsKey(download_items_, download));
       download_items_.erase(download);
       download->RemoveObserver(this);
       break;
     }
 
-    case DownloadItem::REMOVING:
     case DownloadItem::INTERRUPTED:
     case DownloadItem::CANCELLED: {
       DCHECK(ContainsKey(download_items_, download));
       download_items_.erase(download);
       download->RemoveObserver(this);
       break;
     }
 
     default:
       break;
   }
 }
 
+void DownloadCompletionObserver::OnDownloadDestroyed(DownloadItem* download) {
+  DCHECK(ContainsKey(download_items_, download));
+  download_items_.erase(download);
+  download->RemoveObserver(this);
+}
+
 void DownloadCompletionObserver::ClearDownloadItems() {
   for (std::set<DownloadItem*>::iterator it = download_items_.begin();
        it != download_items_.end(); ++it) {
     (*it)->RemoveObserver(this);
   }
   download_items_.clear();
 }