aura: Remove event-dispatch methods from WindowTreeHostDelegate interface.

ui/events/event_source.cc

 // Copyright 2013 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/events/event_source.h"
 
 #include "ui/events/event_processor.h"
 
 namespace ui {
 
-void EventSource::SendEventToProcessor(Event* event) {
+EventDispatchDetails EventSource::SendEventToProcessor(Event* event) {
   EventProcessor* processor = GetEventProcessor();
   CHECK(processor);
-  EventDispatchDetails details = processor->OnEventFromSource(event);
-  if (details.dispatcher_destroyed)
-    return;
+  return processor->OnEventFromSource(event);
 }
 
 }  // namespace ui