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

ui/aura/test/test_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/aura/test/test_event_handler.h"
 
 namespace aura {
 namespace test {
 
 TestEventHandler::TestEventHandler()
@@ skipping 11 matching lines @@
   num_mouse_events_ = 0;
   num_scroll_events_ = 0;
   num_touch_events_ = 0;
   num_gesture_events_ = 0;
 }
 
 void TestEventHandler::OnKeyEvent(ui::KeyEvent* event) {
   num_key_events_++;
 }
 
-ui::EventResult TestEventHandler::OnMouseEvent(ui::MouseEvent* event) {
+void TestEventHandler::OnMouseEvent(ui::MouseEvent* event) {
   num_mouse_events_++;
-  return ui::ER_UNHANDLED;
 }
 
 void TestEventHandler::OnScrollEvent(ui::ScrollEvent* event) {
   num_scroll_events_++;
 }
 
 void TestEventHandler::OnTouchEvent(ui::TouchEvent* event) {
   num_touch_events_++;
 }
 
 void TestEventHandler::OnGestureEvent(ui::GestureEvent* event) {
   num_gesture_events_++;
 }
 
 }  // namespace test
 }  // namespace aura