NTP: Record TileType metrics also on desktop

components/ntp_tiles/tile_visual_type.h

 // Copyright 2017 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 COMPONENTS_NTP_TILES_TILE_VISUAL_TYPE_H_
 #define COMPONENTS_NTP_TILES_TILE_VISUAL_TYPE_H_
 
 namespace ntp_tiles {
 
 // The visual type of an NTP tile.
 //
 // These values must stay in sync with the NTPTileVisualType enum in
 // histograms.xml.
 //
 // A Java counterpart will be generated for this enum.
 // GENERATED_JAVA_ENUM_PACKAGE: org.chromium.chrome.browser.suggestions
 enum TileVisualType {
   // The icon or thumbnail hasn't loaded yet.
   NONE = 0,
   // The item displays a site's actual favicon or touch icon.
   ICON_REAL = 1,
   // The item displays a color derived from the site's favicon or touch icon.
   ICON_COLOR = 2,
   // The item displays a default gray box in place of an icon.
   ICON_DEFAULT = 3,
-  // The number of different tile types that get recorded. Entries below this
-  // are not recorded in UMA.
-  NUM_RECORDED_TILE_TYPES,
-
   // Deleted: THUMBNAIL_LOCAL = 4
   // Deleted: THUMBNAIL_SERVER = 5
   // Deleted: THUMBNAIL_DEFAULT = 6
+  // The item displays a thumbnail of the page. Used on desktop.
+  THUMBNAIL = 7,
+  // The item wants to display a thumbnail of the page, but it failed to load.
+  // Used on desktop.
+  THUMBNAIL_FAILED = 8,
+  // The maximum tile type value that gets recorded in UMA.
+  LAST_RECORDED_TILE_TYPE = THUMBNAIL_FAILED,
 
-  // The item displays a thumbnail of the page. Used on desktop.
-  THUMBNAIL,
   // The tile type has not been determined yet. Used on iOS, until we can detect
   // when all tiles have loaded.
   UNKNOWN_TILE_TYPE,
+
+  TILE_TYPE_MAX = UNKNOWN_TILE_TYPE
 };
 
 }  // namespace ntp_tiles
 
 #endif  // COMPONENTS_NTP_TILES_TILE_VISUAL_TYPE_H_