Desktop NTP: Add a UMA metric NewTabPage.TilesReceivedTime

chrome/common/search/ntp_logging_events.h

 // Copyright 2013 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_COMMON_SEARCH_NTP_LOGGING_EVENTS_H_
 #define CHROME_COMMON_SEARCH_NTP_LOGGING_EVENTS_H_
 
 // The different types of events that are logged from the NTP. This enum is used
-// to transfer information from the NTP javascript to the renderer and is not
+// to transfer information from the NTP javascript to the renderer and is *not*
 // used as a UMA enum histogram's logged value.
 // Note: Keep in sync with browser/resources/local_ntp/most_visited_single.js
 enum NTPLoggingEventType {
-  // A suggestion coming from the server was rendered.
   // Deleted: NTP_SERVER_SIDE_SUGGESTION = 0,
-
-  // A suggestion coming from the client was rendered.
   // Deleted: NTP_CLIENT_SIDE_SUGGESTION = 1,
-
-  // Indicates a tile was rendered, no matter if it's a thumbnail, a gray tile
-  // or an external tile.
   // Deleted: NTP_TILE = 2,
-
-  // The tile uses a local thumbnail image.
   // Deleted: NTP_THUMBNAIL_TILE = 3,
-
-  // Used when no thumbnail is specified and a gray tile with the domain is used
-  // as the main tile.
   // Deleted: NTP_GRAY_TILE = 4,
-
-  // The visuals of that tile are handled externally by the page itself.
   // Deleted: NTP_EXTERNAL_TILE = 5,
-
-  // There was an error in loading both the thumbnail image and the fallback
-  // (if it was provided), resulting in a grey tile.
   // Deleted: NTP_THUMBNAIL_ERROR = 6,
-
-  // Used a gray tile with the domain as the fallback for a failed thumbnail.
   // Deleted: NTP_GRAY_TILE_FALLBACK = 7,
-
-  // The visuals of that tile's fallback are handled externally.
   // Deleted: NTP_EXTERNAL_TILE_FALLBACK = 8,
-
   // Deleted: NTP_MOUSEOVER = 9
-
-  // A NTP Tile has finished loading (successfully or failing). Logged only by
-  // the multi-iframe version of the NTP.
   // Deleted: NTP_TILE_LOADED = 10,
 
   // All NTP tiles have finished loading (successfully or failing). Logged only
   // by the single-iframe version of the NTP.
   NTP_ALL_TILES_LOADED = 11,
 
-  NTP_EVENT_TYPE_LAST = NTP_ALL_TILES_LOADED
+  // The data for all NTP tiles (title, URL, etc, but not the thumbnail image)
+  // has been received by the most visited iframe. In contrast to
+  // NTP_ALL_TILES_LOADED, this is recorded before the actual DOM elements have
+  // loaded (in particular the thumbnail images). Logged only by the
+  // single-iframe version of the NTP.
+  NTP_ALL_TILES_RECEIVED = 12,
+
+  NTP_EVENT_TYPE_LAST = NTP_ALL_TILES_RECEIVED
 };
 
 #endif  // CHROME_COMMON_SEARCH_NTP_LOGGING_EVENTS_H_