events: Update key-event handlers to not return EventResult.

ui/base/events/event_target.cc

Index: ui/base/events/event_target.cc
diff --git a/ui/base/events/event_target.cc b/ui/base/events/event_target.cc
index c587877160a0fd69e3d4db772c34f5018c9b8720..649c72211cf3364ec2675808a3047206eed2abc2 100644
--- a/ui/base/events/event_target.cc
+++ b/ui/base/events/event_target.cc
@@ -52,9 +52,10 @@ void EventTarget::OnEvent(Event* event) {
     EventHandler::OnEvent(event);
 }
 
-EventResult EventTarget::OnKeyEvent(KeyEvent* event) {
+void EventTarget::OnKeyEvent(KeyEvent* event) {
   CHECK_EQ(this, event->target());
-  return target_handler_ ? target_handler_->OnKeyEvent(event) : ER_UNHANDLED;
+  if (target_handler_)
+    target_handler_->OnKeyEvent(event);
 }
 
 EventResult EventTarget::OnMouseEvent(MouseEvent* event) {