events: Dispatch all events through EventHandler::OnEvent from the dispatcher.

ui/base/events/event_handler.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/base/events/event_handler.h"
 
+#include "ui/base/events/event.h"
+
 namespace ui {
 
 EventHandler::EventHandler() {
 }
 
 EventHandler::~EventHandler() {
 }
 
 EventResult EventHandler::OnEvent(Event* event) {
+  if (event->IsKeyEvent())
+    return OnKeyEvent(static_cast<KeyEvent*>(event));
+  if (event->IsMouseEvent())
+    return OnMouseEvent(static_cast<MouseEvent*>(event));
+  if (event->IsScrollEvent())
+    return OnScrollEvent(static_cast<ScrollEvent*>(event));
+  if (event->IsTouchEvent())
+    return OnTouchEvent(static_cast<TouchEvent*>(event));
+  if (event->IsGestureEvent())
+    return OnGestureEvent(static_cast<GestureEvent*>(event));
   return ui::ER_UNHANDLED;
 }
 
 EventResult EventHandler::OnKeyEvent(KeyEvent* event) {
   return ui::ER_UNHANDLED;
 }
 
 EventResult EventHandler::OnMouseEvent(MouseEvent* event) {
   return ui::ER_UNHANDLED;
 }
 
 EventResult EventHandler::OnScrollEvent(ScrollEvent* event) {
   return ui::ER_UNHANDLED;
 }
 
 EventResult EventHandler::OnTouchEvent(TouchEvent* event) {
   return ui::ER_UNHANDLED;
 }
 
 EventResult EventHandler::OnGestureEvent(GestureEvent* event) {
   return ui::ER_UNHANDLED;
 }
 
 }  // namespace ui