[ash-md] Makes Ctrl+W accelerator close a selected window in overview mode

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 108 matching lines @@
 
   // Thumbnail sized overview of windows triggered by pressing the overview key.
   UMA_WINDOW_OVERVIEW,
 
   // User selected a window in overview mode different from the
   // 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,
+
+  // Closing a window in overview mode by clicking the 'X' button.
+  UMA_WINDOW_OVERVIEW_CLOSE_BUTTON,
+
+  // Closing a window in overview mode by pressing Ctrl+w shortcut.
+  UMA_WINDOW_OVERVIEW_CLOSE_KEY,
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_METRICS_USER_METRICS_ACTION_H_