mash: Convert OnWindowInputEventAck to use an enum for handled status

components/mus/public/cpp/input_event_handler.h

 // Copyright 2015 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.
 
 #ifndef COMPONENTS_MUS_PUBLIC_CPP_INPUT_EVENT_HANDLER_H_
 #define COMPONENTS_MUS_PUBLIC_CPP_INPUT_EVENT_HANDLER_H_
 
 #include "base/callback_forward.h"
 #include "base/memory/scoped_ptr.h"
 
 namespace ui {
 class Event;
 }
 
 namespace mus {
 
 class Window;
 
+namespace mojom {
+enum class EventResult;
+}
+
 // Responsible for processing input events for mus::Window.
 class InputEventHandler {
  public:
   // The event handler can asynchronously ack the event by taking ownership of
-  // the |ack_callback|. The callback takes a bool representing whether the
+  // the |ack_callback|. The callback takes an EventResult indicating if the
   // handler has consumed the event. If the handler does not take ownership of
   // the callback, then WindowTreeClientImpl will ack the event as not consumed.
   virtual void OnWindowInputEvent(
       Window* target,
       const ui::Event& event,
-      scoped_ptr<base::Callback<void(bool)>>* ack_callback) = 0;
+      scoped_ptr<base::Callback<void(mojom::EventResult)>>* ack_callback) = 0;
 
  protected:
   virtual ~InputEventHandler() {}
 };
 
 }  // namespace mus
 
 #endif  // COMPONENTS_MUS_PUBLIC_CPP_INPUT_EVENT_HANDLER_H_