Add new UMA stats to get a handle on Downloads UI Usage

content/browser/download/download_item.h

 // 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.
 //
 // 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 260 matching lines @@
   std::string original_mime_type() const { return original_mime_type_; }
   std::string referrer_charset() const { return referrer_charset_; }
   int64 total_bytes() const { return total_bytes_; }
   void set_total_bytes(int64 total_bytes) {
     total_bytes_ = total_bytes;
   }
   int64 received_bytes() const { return received_bytes_; }
   int32 id() const { return download_id_; }
   DownloadId global_id() const;
   base::Time start_time() const { return start_time_; }
+  base::Time end_time() const { return end_time_; }
   void set_db_handle(int64 handle) { db_handle_ = handle; }
   int64 db_handle() const { return db_handle_; }
   DownloadManager* download_manager() { return download_manager_; }
   bool is_paused() const { return is_paused_; }
   bool open_when_complete() const { return open_when_complete_; }
   void set_open_when_complete(bool open) { open_when_complete_ = open; }
   bool file_externally_removed() const { return file_externally_removed_; }
   SafetyState safety_state() const { return safety_state_; }
   // Why |safety_state_| is not SAFE.
   DangerType GetDangerType() const;
@@ skipping 134 matching lines @@
 
   // The current state of this download
   DownloadState state_;
 
   // The views of this item in the download shelf and download tab
   ObserverList<Observer> observers_;
 
   // Time the download was started
   base::Time start_time_;
 
+  // Time the download completed
+  base::Time end_time_;
+
   // Our persistent store handle
   int64 db_handle_;
 
   // Timer for regularly updating our observers
   base::RepeatingTimer<DownloadItem> update_timer_;
 
   // Our owning object
   DownloadManager* download_manager_;
 
   // In progress downloads may be paused by the user, we note it here
@@ skipping 33 matching lines @@
   // only.
   bool open_enabled_;
 
   // Did the delegate delay calling Complete on this download?
   bool delegate_delayed_complete_;
 
   DISALLOW_COPY_AND_ASSIGN(DownloadItem);
 };
 
 #endif  // CONTENT_BROWSER_DOWNLOAD_DOWNLOAD_ITEM_H_