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      1 // Copyright (c) 2012 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 CHROME_BROWSER_CHROMEOS_XINPUT_HIERARCHY_CHANGED_EVENT_LISTENER_H_
      6 #define CHROME_BROWSER_CHROMEOS_XINPUT_HIERARCHY_CHANGED_EVENT_LISTENER_H_
      7 
      8 #include "base/memory/singleton.h"
      9 #include "base/message_loop/message_loop.h"
     10 #include "base/observer_list.h"
     11 #include "chrome/browser/chromeos/device_hierarchy_observer.h"
     12 
     13 typedef union _XEvent XEvent;
     14 
     15 namespace chromeos {
     16 
     17 // XInputHierarchyChangedEventListener listens for an XI_HierarchyChanged event,
     18 // which is sent to Chrome when X detects a system or USB keyboard (or mouse),
     19 // then tells X to change the current XKB keyboard layout. Start by just calling
     20 // instance() to get it going.
     21 class XInputHierarchyChangedEventListener
     22     : public base::MessageLoopForUI::Observer {
     23  public:
     24   static XInputHierarchyChangedEventListener* GetInstance();
     25 
     26   void Stop();
     27 
     28   void AddObserver(DeviceHierarchyObserver* observer);
     29   void RemoveObserver(DeviceHierarchyObserver* observer);
     30 
     31  private:
     32   // Defines the delete on exit Singleton traits we like.  Best to have this
     33   // and const/dest private as recommended for Singletons.
     34   friend struct DefaultSingletonTraits<XInputHierarchyChangedEventListener>;
     35 
     36   XInputHierarchyChangedEventListener();
     37   virtual ~XInputHierarchyChangedEventListener();
     38 
     39   void Init();
     40   void StopImpl();
     41 
     42   // MessageLoopForUI::Observer overrides.
     43   virtual base::EventStatus WillProcessEvent(
     44       const base::NativeEvent& event) OVERRIDE;
     45   virtual void DidProcessEvent(const base::NativeEvent& event) OVERRIDE;
     46 
     47   // Returns true if the event was processed, false otherwise.
     48   virtual bool ProcessedXEvent(XEvent* xevent);
     49 
     50   // Notify observers that a device has been added/removed.
     51   void NotifyDeviceHierarchyChanged();
     52 
     53   bool stopped_;
     54   int xiopcode_;
     55 
     56   ObserverList<DeviceHierarchyObserver> observer_list_;
     57 
     58   DISALLOW_COPY_AND_ASSIGN(XInputHierarchyChangedEventListener);
     59 };
     60 
     61 }  // namespace chromeos
     62 
     63 #endif  // CHROME_BROWSER_CHROMEOS_XINPUT_HIERARCHY_CHANGED_EVENT_LISTENER_H_
     64