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

ash/common/metrics/user_metrics_action.h

Index: ash/common/metrics/user_metrics_action.h
diff --git a/ash/common/metrics/user_metrics_action.h b/ash/common/metrics/user_metrics_action.h
index b53871053839ac1145cd0b09abf9b4a3c9bd2d9c..1d38ab266cb16dd41039cda94b5fe22e1cc647ae 100644
--- a/ash/common/metrics/user_metrics_action.h
+++ b/ash/common/metrics/user_metrics_action.h
@@ -126,6 +126,12 @@ enum UserMetricsAction {
 
   // 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