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

chrome/browser/history/history_backend.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_BACKEND_H_
 #define CHROME_BROWSER_HISTORY_HISTORY_BACKEND_H_
 #pragma once
 
 #include <string>
 #include <utility>
@@ skipping 228 matching lines @@
   void SetFaviconOutOfDateForPage(const GURL& page_url);
 
   void SetImportedFavicons(
       const std::vector<ImportedFaviconUsage>& favicon_usage);
 
   // Downloads -----------------------------------------------------------------
 
   void GetNextDownloadId(scoped_refptr<DownloadNextIdRequest> request);
   void QueryDownloads(scoped_refptr<DownloadQueryRequest> request);
   void CleanUpInProgressEntries();
-  void UpdateDownload(int64 received_bytes, int32 state, int64 db_handle);
+  void UpdateDownload(DownloadItemData data);

[brettw, 2011/10/01 16:45:45]

This should be a const ref. The runnable methods know to copy const refs when
sending to the background thread, but you're requiring yet another copy for it
to call your function.

[benjhayden, 2011/10/03 20:54:39]

Done.

   void UpdateDownloadPath(const FilePath& path, int64 db_handle);
   void CreateDownload(scoped_refptr<DownloadCreateRequest> request,
                       int32 id,
                       const DownloadPersistentStoreInfo& info);
   void RemoveDownload(int64 db_handle);
   void RemoveDownloadsBetween(const base::Time remove_begin,
                               const base::Time remove_end);
   void RemoveDownloads(const base::Time remove_end);
 
   // Segment usage -------------------------------------------------------------
@@ skipping 361 matching lines @@
   // Publishes the history to all indexers which are registered to receive
   // history data from us. Can be NULL if there are no listeners.
   scoped_ptr<HistoryPublisher> history_publisher_;
 
   DISALLOW_COPY_AND_ASSIGN(HistoryBackend);
 };
 
 }  // namespace history
 
 #endif  // CHROME_BROWSER_HISTORY_HISTORY_BACKEND_H_