Fix for Ash shortcuts unexpectedly working in system model dialog

ash/accelerators/accelerator_controller.h

Index: ash/accelerators/accelerator_controller.h
diff --git a/ash/accelerators/accelerator_controller.h b/ash/accelerators/accelerator_controller.h
index 0e2ddf4f81ce67c5fb2fc7b17c0dbc519a06fca5..672e89521c155c551c8896d78e0c8066a126db12 100644
--- a/ash/accelerators/accelerator_controller.h
+++ b/ash/accelerators/accelerator_controller.h
@@ -115,6 +115,8 @@ class ASH_EXPORT AcceleratorController : public ui::AcceleratorTarget {
   std::set<int> actions_allowed_at_login_screen_;
   // Actions allowed when the screen is locked.
   std::set<int> actions_allowed_at_lock_screen_;
+  // Actions allowed when a modal window is up.
+  std::set<int> actions_allowed_at_modal_window_;
   // Reserved actions. See accelerator_table.h for details.
   std::set<int> reserved_actions_;