mash: Convert OnWindowInputEventAck to use an enum for handled status

ui/views/mus/platform_window_mus.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 UI_VIEWS_MUS_PLATFORM_WINDOW_MUS_H_
 #define UI_VIEWS_MUS_PLATFORM_WINDOW_MUS_H_
 
 #include <stdint.h>
 
 #include <string>
@@ skipping 68 matching lines @@
       mus::Window* window,
       const std::string& name,
       const std::vector<uint8_t>* old_data,
       const std::vector<uint8_t>* new_data) override;
   void OnRequestClose(mus::Window* window) override;
 
   // mus::InputEventHandler:
   void OnWindowInputEvent(
       mus::Window* view,
       const ui::Event& event,
-      std::unique_ptr<base::Callback<void(bool)>>* ack_callback) override;
+      std::unique_ptr<base::Callback<void(mus::mojom::EventResult)>>*
+          ack_callback) override;
 
   ui::PlatformWindowDelegate* delegate_;
   mus::Window* mus_window_;
   mus::mojom::ShowState show_state_;
   mus::mojom::Cursor last_cursor_;
 
   // True if OnWindowDestroyed() has been received.
   bool mus_window_destroyed_;
 
   std::unique_ptr<bitmap_uploader::BitmapUploader> bitmap_uploader_;
   std::unique_ptr<ui::ViewProp> prop_;
 #ifndef NDEBUG
   std::unique_ptr<base::WeakPtrFactory<PlatformWindowMus>> weak_factory_;
 #endif
 
   DISALLOW_COPY_AND_ASSIGN(PlatformWindowMus);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_MUS_PLATFORM_WINDOW_MUS_H_