Fix accelerator history tracking

ui/base/accelerators/accelerator_history.h

Index: ui/base/accelerators/accelerator_history.h
diff --git a/ui/base/accelerators/accelerator_history.h b/ui/base/accelerators/accelerator_history.h
index 22aaf1fcc8d9ecb99182784929ae50c7cbe11bf5..ee63a5723fe6ed98b07ed24312b5f8d660d27de3 100644
--- a/ui/base/accelerators/accelerator_history.h
+++ b/ui/base/accelerators/accelerator_history.h
@@ -5,12 +5,11 @@
 #ifndef UI_BASE_ACCELERATORS_ACCELERATOR_HISTORY_H_
 #define UI_BASE_ACCELERATORS_ACCELERATOR_HISTORY_H_
 
+#include <set>
+
 #include "base/macros.h"
-#include "base/memory/singleton.h"
 #include "ui/base/accelerators/accelerator.h"
 #include "ui/base/ui_base_export.h"
-#include "ui/events/event.h"
-#include "ui/events/event_handler.h"
 
 namespace ui {
 
@@ -40,6 +39,8 @@ class UI_BASE_EXPORT AcceleratorHistory {
   Accelerator current_accelerator_;
   Accelerator previous_accelerator_;
 
+  std::set<KeyboardCode> currently_pressed_keys_;
+
   DISALLOW_COPY_AND_ASSIGN(AcceleratorHistory);
 };