Support NSFlagsChanged in ui::EventFromNative.

ui/events/cocoa/cocoa_event_utils.h

Index: ui/events/cocoa/cocoa_event_utils.h
diff --git a/ui/events/cocoa/cocoa_event_utils.h b/ui/events/cocoa/cocoa_event_utils.h
index 71ddab95e788483290d3b7128bacad60d190cf2a..b1ba7801f171c43f92e08ad328fc51103b43d13d 100644
--- a/ui/events/cocoa/cocoa_event_utils.h
+++ b/ui/events/cocoa/cocoa_event_utils.h
@@ -24,6 +24,11 @@ EVENTS_EXPORT int EventFlagsFromModifiers(NSUInteger modifiers);
 // scratch.
 EVENTS_EXPORT int EventFlagsFromNSEventWithModifiers(NSEvent* event,
                                                      NSUInteger modifiers);
+
+// Returns true for |NSKeyUp| and for |NSFlagsChanged| when modifier key was
+// released.
+EVENTS_EXPORT bool IsKeyUpEvent(NSEvent* event);
+
 }  // namespace ui
 
 #endif  // UI_EVENTS_COCOA_COCOA_EVENT_UTILS_H_