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 84 matching lines @@
     return NavigatorGamepad::from(navigator).webkitGamepads();
 }
 
 GamepadList* NavigatorGamepad::getGamepads(Navigator& navigator)
 {
     return NavigatorGamepad::from(navigator).gamepads();
 }
 
 WebKitGamepadList* NavigatorGamepad::webkitGamepads()
 {
+    m_wasPolled = true;
     if (!m_webkitGamepads)
         m_webkitGamepads = WebKitGamepadList::create();
     if (window()) {
         startUpdating();
         sampleGamepads<WebKitGamepad>(m_webkitGamepads.get());
     }
     return m_webkitGamepads.get();
 }
 
 GamepadList* NavigatorGamepad::gamepads()
 {
+    m_wasPolled = true;
     if (!m_gamepads)
         m_gamepads = GamepadList::create();
     if (window()) {
         startUpdating();
         sampleGamepads<Gamepad>(m_gamepads.get());
     }
     return m_gamepads.get();
 }
 
 void NavigatorGamepad::trace(Visitor* visitor)
@@ skipping 27 matching lines @@
     m_gamepads->set(change.index, gamepad);
 
     const AtomicString& eventName = change.pad.connected ? EventTypeNames::gamepadconnected : EventTypeNames::gamepaddisconnected;
     window()->dispatchEvent(GamepadEvent::create(eventName, false, true, gamepad));
 }
 
 NavigatorGamepad::NavigatorGamepad(LocalFrame* frame)
     : DOMWindowProperty(frame)
     , DeviceEventControllerBase(frame ? frame->page() : 0)
     , DOMWindowLifecycleObserver(frame ? frame->domWindow() : 0)
+    , m_wasPolled(false)
 {
 }
 
 NavigatorGamepad::~NavigatorGamepad()
 {
 }
 
 const char* NavigatorGamepad::supplementName()
 {
     return "NavigatorGamepad";
@@ skipping 48 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_wasPolled))
+        startUpdating();
+    else
+        stopUpdating();
+}
+
 } // namespace WebCore