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

chrome/browser/history/history.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.
 
 #ifndef CHROME_BROWSER_HISTORY_HISTORY_H_
 #define CHROME_BROWSER_HISTORY_HISTORY_H_
 #pragma once
 
 #include <set>
 #include <vector>
@@ skipping 431 matching lines @@
   Handle QueryDownloads(CancelableRequestConsumerBase* consumer,
                         DownloadQueryCallback* callback);
 
   // Begins a request to clean up entries that has been corrupted (because of
   // the crash, for example).
   void CleanUpInProgressEntries();
 
   // Called to update the history service about the current state of a download.
   // This is a 'fire and forget' query, so just pass the relevant state info to
   // the database with no need for a callback.
-  void UpdateDownload(int64 received_bytes, int32 state, int64 db_handle);
+  void UpdateDownload(int64 received_bytes,
+                      int32 state,
+                      const base::Time& end_time,
+                      int64 db_handle);
 
   // Called to update the history service about the path of a download.
   // This is a 'fire and forget' query.
   void UpdateDownloadPath(const FilePath& path, int64 db_handle);
 
   // Permanently remove a download from the history system. This is a 'fire and
   // forget' operation.
   void RemoveDownload(int64 db_handle);
 
   // Permanently removes all completed download from the history system within
   // the specified range. This function does not delete downloads that are in
   // progress or in the process of being cancelled. This is a 'fire and forget'
   // operation. You can pass is_null times to get unbounded time in either or
   // both directions.
   void RemoveDownloadsBetween(base::Time remove_begin, base::Time remove_end);
 
+  // Sets the download record |opened| flag.
+  void MarkDownloadOpened(int64 db_handle);
+
   // Visit Segments ------------------------------------------------------------
 
   typedef Callback2<Handle, std::vector<PageUsageData*>*>::Type
       SegmentQueryCallback;
 
   // Query usage data for all visit segments since the provided time.
   //
   // The request is performed asynchronously and can be cancelled by using the
   // returned handle.
   //
@@ skipping 400 matching lines @@
   BookmarkService* bookmark_service_;
   bool no_db_;
 
   // True if needs top site migration.
   bool needs_top_sites_migration_;
 
   DISALLOW_COPY_AND_ASSIGN(HistoryService);
 };
 
 #endif  // CHROME_BROWSER_HISTORY_HISTORY_H_