Refactor compositor event handling path to be callback-based

content/renderer/mus/render_widget_mus_connection.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 CONTENT_RENDERER_MUS_RENDER_WIDGET_MUS_CONNECTION_H_
 #define CONTENT_RENDERER_MUS_RENDER_WIDGET_MUS_CONNECTION_H_
 
 #include "base/macros.h"
 #include "base/threading/thread_checker.h"
 #include "cc/output/output_surface.h"
@@ skipping 46 matching lines @@
   void NotifyInputEventHandled(blink::WebInputEvent::Type handled_type,
                                InputEventAckState ack_result) override;
   void SetInputHandler(RenderWidgetInputHandler* input_handler) override;
   void UpdateTextInputState(ShowIme show_ime,
                             ChangeSource change_source) override;
   bool WillHandleGestureEvent(const blink::WebGestureEvent& event) override;
   bool WillHandleMouseEvent(const blink::WebMouseEvent& event) override;
 
   void OnConnectionLost();
   void OnWindowInputEvent(
-      std::unique_ptr<blink::WebInputEvent> input_event,
+      ui::ScopedWebInputEvent input_event,
       const base::Callback<void(ui::mojom::EventResult)>& ack);
 
   const int routing_id_;
   RenderWidgetInputHandler* input_handler_;
   std::unique_ptr<ui::WindowSurfaceBinding> window_surface_binding_;
   scoped_refptr<CompositorMusConnection> compositor_mus_connection_;
 
   base::Callback<void(ui::mojom::EventResult)> pending_ack_;
 
   // Used to verify single threaded access.
   base::ThreadChecker thread_checker_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderWidgetMusConnection);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_MUS_RENDER_WIDGET_MUS_CONNECTION_H_