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

ui/base/events/event_handler.cc

Index: ui/base/events/event_handler.cc
diff --git a/ui/base/events/event_handler.cc b/ui/base/events/event_handler.cc
index 93347a522c3f81da90d77e5d82d6f0cd11055e4a..ea9048e409de0e8e2b52f9cb550f574b774755be 100644
--- a/ui/base/events/event_handler.cc
+++ b/ui/base/events/event_handler.cc
@@ -4,6 +4,8 @@
 
 #include "ui/base/events/event_handler.h"
 
+#include "ui/base/events/event.h"
+
 namespace ui {
 
 EventHandler::EventHandler() {
@@ -13,6 +15,16 @@ 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;
 }