Adding active_downloads_ map.

chrome/browser/download/download_item.h

 // Copyright (c) 2010 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.
 //
 // Each download is represented by a DownloadItem, and all DownloadItems
 // are owned by the DownloadManager which maintains a global list of all
 // downloads. DownloadItems are created when a user initiates a download,
 // and exist for the duration of the browser life time.
 //
 // Download observers:
@@ skipping 16 matching lines @@
 #include "base/timer.h"
 #include "googleurl/src/gurl.h"
 
 class DownloadFileManager;
 class DownloadManager;
 struct DownloadCreateInfo;
 
 // One DownloadItem per download. This is the model class that stores all the
 // state for a download. Multiple views, such as a tab's download shelf and the
 // Destination tab's download view, may refer to a given DownloadItem.
+//
+// This is intended to be used only on the UI thread.
 class DownloadItem {
  public:
   enum DownloadState {
     IN_PROGRESS,
     COMPLETE,
     CANCELLED,
     REMOVING
   };
 
   enum SafetyState {
@@ skipping 289 matching lines @@
   // Did the user open the item either directly or indirectly (such as by
   // setting always open files of this type)? The shelf also sets this field
   // when the user closes the shelf before the item has been opened but should
   // be treated as though the user opened it.
   bool opened_;
 
   DISALLOW_COPY_AND_ASSIGN(DownloadItem);
 };
 
 #endif  // CHROME_BROWSER_DOWNLOAD_DOWNLOAD_ITEM_H_