Register a separate default ui::EventTarget for Aura (Ash) to ensure that it does not interfere wit…

ui/aura/client/event_client.h

 // Copyright (c) 2012 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_AURA_CLIENT_EVENT_CLIENT_H_
 #define UI_AURA_CLIENT_EVENT_CLIENT_H_
 
 #include "ui/aura/aura_export.h"
 #include "ui/aura/window.h"
 
 namespace aura {
 
 class Event;
 class RootWindow;
 
 namespace client {
 
 // An interface implemented by an object that alters event processing.
 class AURA_EXPORT EventClient {
  public:
   // Returns true if events can be processed by |window| or any of its children.
   virtual bool CanProcessEventsWithinSubtree(const Window* window) const = 0;
 
+  // Returns the top level EventTarget for the current environment.
+  virtual ui::EventTarget* GetToplevelEventTarget() = 0;
+
  protected:
   virtual ~EventClient() {}
 };
 
 // Sets/Gets the event client on the RootWindow.
 AURA_EXPORT void SetEventClient(RootWindow* root_window, EventClient* client);
 AURA_EXPORT EventClient* GetEventClient(const RootWindow* root_window);
 
 }  // namespace clients
 }  // namespace aura
 
 #endif  // UI_AURA_CLIENT_EVENT_CLIENT_H_