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      1 // Copyright 2014 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef UI_EVENTS_PLATFORM_PLATFORM_EVENT_OBSERVER_H_
      6 #define UI_EVENTS_PLATFORM_PLATFORM_EVENT_OBSERVER_H_
      7 
      8 #include "ui/events/events_export.h"
      9 #include "ui/events/platform/platform_event_types.h"
     10 
     11 namespace ui {
     12 
     13 // PlatformEventObserver can be installed on a PlatformEventSource, and it
     14 // receives all events that are dispatched to the dispatchers.
     15 class EVENTS_EXPORT PlatformEventObserver {
     16  public:
     17   // This is called before the dispatcher receives the event.
     18   virtual void WillProcessEvent(const PlatformEvent& event) = 0;
     19 
     20   // This is called after the event has been dispatched to the dispatcher(s).
     21   virtual void DidProcessEvent(const PlatformEvent& event) = 0;
     22 
     23  protected:
     24   virtual ~PlatformEventObserver() {}
     25 };
     26 
     27 }  // namespace ui
     28 
     29 #endif  // UI_EVENTS_PLATFORM_PLATFORM_EVENT_OBSERVER_H_
     30