Notify the browser when the page lost interest about gamepads

Source/modules/gamepad/NavigatorGamepad.cpp

 /*
  * Copyright (C) 2011, Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
  *
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 210 matching lines @@
         && !window->hasEventListeners(EventTypeNames::gamepaddisconnected)) {
         m_hasEventListener = false;
     }
 }
 
 void NavigatorGamepad::didRemoveAllEventListeners(LocalDOMWindow*)
 {
     m_hasEventListener = false;
 }
 
+void NavigatorGamepad::pageVisibilityChanged()
+{
+    // Inform the embedder whether it needs to provide gamepad data for us.
+    if (page()->visibilityState() == PageVisibilityStateVisible && (m_hasEventListener || m_gamepads || m_webkitGamepads))
+        startUpdating();
+    else
+        stopUpdating();
+}
+
 } // namespace WebCore