Added UMA metrics for the system update UI in the status area.

ash/common/metrics/user_metrics_action.h

 // Copyright 2016 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 ASH_COMMON_METRICS_USER_METRICS_ACTION_H_
 #define ASH_COMMON_METRICS_USER_METRICS_ACTION_H_
 
 namespace ash {
 
 // Ash-owned user metrics.
@@ skipping 73 matching lines @@
   UMA_STATUS_AREA_ENABLE_WIFI,
   UMA_STATUS_AREA_ENABLE_VIRTUAL_KEYBOARD,
   UMA_STATUS_AREA_IME_SHOW_DETAILED,
   UMA_STATUS_AREA_IME_SWITCH_MODE,
   UMA_STATUS_AREA_MENU_OPENED,
   UMA_STATUS_AREA_NETWORK_JOIN_OTHER_CLICKED,
   UMA_STATUS_AREA_NETWORK_SETTINGS_CLICKED,
   UMA_STATUS_AREA_SHOW_NETWORK_CONNECTION_DETAILS,
   UMA_STATUS_AREA_SHOW_VPN_CONNECTION_DETAILS,
   UMA_STATUS_AREA_SIGN_OUT,
+  UMA_STATUS_AREA_UPDATE_DEFAULT_SELECTED,

[James Cook, 2016/07/08 18:09:00]

nit: I would call this "OS_UPDATE" or "UPDATER" or something else. Otherwise it
sounds like a status-area-update.

[bruthig, 2016/07/08 20:24:00]

Done.

   UMA_STATUS_AREA_VPN_ADD_BUILT_IN_CLICKED,
   UMA_STATUS_AREA_VPN_ADD_THIRD_PARTY_CLICKED,
   UMA_STATUS_AREA_VPN_DISCONNECT_CLICKED,
   UMA_STATUS_AREA_VPN_SETTINGS_CLICKED,
   UMA_TOGGLE_MAXIMIZE_CAPTION_CLICK,
   UMA_TOGGLE_MAXIMIZE_CAPTION_GESTURE,
   UMA_TOGGLE_SINGLE_AXIS_MAXIMIZE_BORDER_CLICK,
   UMA_TOUCHPAD_GESTURE_OVERVIEW,
   UMA_TOUCHSCREEN_TAP_DOWN,
   UMA_TRAY_HELP,
@@ skipping 20 matching lines @@
   // previously-active window.
   UMA_WINDOW_OVERVIEW_ACTIVE_WINDOW_CHANGED,
 
   // Selecting a window in overview mode by pressing the enter key.
   UMA_WINDOW_OVERVIEW_ENTER_KEY,
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_METRICS_USER_METRICS_ACTION_H_