mash: Close the system tray bubble on click outside its bounds

ash/system/chromeos/session/logout_button_tray.cc

Index: ash/system/chromeos/session/logout_button_tray.cc
diff --git a/ash/system/chromeos/session/logout_button_tray.cc b/ash/system/chromeos/session/logout_button_tray.cc
index da73da562e62b69ed57fa38432dbd5cef9162d28..9deede73f8c844c889628cbed2791f96924e021a 100644
--- a/ash/system/chromeos/session/logout_button_tray.cc
+++ b/ash/system/chromeos/session/logout_button_tray.cc
@@ -123,9 +123,7 @@ void LogoutButtonTray::HideBubbleWithView(
     const views::TrayBubbleView* bubble_view) {
 }
 
-bool LogoutButtonTray::ClickedOutsideBubble() {
-  return false;
-}
+void LogoutButtonTray::ClickedOutsideBubble() {}
 
 void LogoutButtonTray::OnShowLogoutButtonInTrayChanged(bool show) {
   show_logout_button_in_tray_ = show;