Update WindowTree::OnWindowInputEventAck to include handled

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 "components/mus/public/interfaces/input_events.mojom.h"
 
 namespace mus {
 
 class Window;
 
 // 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|. If the handler does not take ownership of the callback,
-  // then WindowTreeClientImpl will ack the event.
-  virtual void OnWindowInputEvent(Window* target,
-                                  mojom::EventPtr event,
-                                  scoped_ptr<base::Closure>* ack_callback) = 0;
+  // the |ack_callback|. The callback takes a bool representing whether 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,
+      mojom::EventPtr event,
+      scoped_ptr<base::Callback<void(bool)>>* ack_callback) = 0;
+
  protected:
   virtual ~InputEventHandler() {}
 };
 
 }  // namespace mus
 
 #endif  // COMPONENTS_MUS_PUBLIC_CPP_INPUT_EVENT_HANDLER_H_