Change system settings based on when mouse/touchpad is connected/disconnected.

chrome/browser/chromeos/xinput_hierarchy_changed_event_listener.h

Index: chrome/browser/chromeos/xinput_hierarchy_changed_event_listener.h
===================================================================
--- chrome/browser/chromeos/xinput_hierarchy_changed_event_listener.h	(revision 115229)
+++ chrome/browser/chromeos/xinput_hierarchy_changed_event_listener.h	(working copy)
@@ -12,6 +12,7 @@
 
 #include "base/memory/singleton.h"
 #include "base/message_loop.h"
+#include "base/observer_list.h"
 
 typedef union _XEvent XEvent;
 
@@ -27,6 +28,16 @@
 
   void Stop();
 
+  // Observers receive notifications when a device has been added/removed.
+  class Observer {

[xiyuan, 2011/12/21 03:38:24]

Think the new preferred way is to have the observer/listener interface in its
own header file.

[achuithb, 2011/12/21 22:15:01]

Done.

+   public:
+    virtual ~Observer() {}

[xiyuan, 2011/12/21 03:38:24]

protected?

[achuithb, 2011/12/21 22:15:01]

Done.

+    virtual void DeviceChanged() = 0;

[xiyuan, 2011/12/21 03:38:24]

Think DeviceTreeChanged or DeviceHierarchyChanged is closer to what this really
means. 

[achuithb, 2011/12/21 22:15:01]

Done.

+  };
+
+  void AddObserver(Observer* observer);
+  void RemoveObserver(Observer* observer);
+
  private:
   // Defines the delete on exit Singleton traits we like.  Best to have this
   // and const/dest private as recommended for Singletons.
@@ -59,9 +70,14 @@
   // Returns true if the event was processed, false otherwise.
   virtual bool ProcessedXEvent(XEvent* xevent);
 
+  // Notify observers that a device has been added/removed.
+  void NotifyDeviceChanged();
+
   bool stopped_;
   int xiopcode_;
 
+  ObserverList<Observer> observer_list_;
+
   DISALLOW_COPY_AND_ASSIGN(XInputHierarchyChangedEventListener);
 };