Gracefully support Navigator Gamepad methods in a detached state.

Source/core/frame/DeviceSensorEventController.cpp

 /*
  * Copyright 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2012 Samsung Electronics. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *  * Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  *  * Redistributions in binary form must reproduce the above copyright
@@ skipping 15 matching lines @@
 
 #include "config.h"
 #include "core/frame/DeviceSensorEventController.h"
 
 #include "core/dom/Document.h"
 #include "core/frame/DOMWindow.h"
 #include "core/page/Page.h"
 
 namespace WebCore {
 
-DeviceSensorEventController::DeviceSensorEventController(Document& document)
-    : PageLifecycleObserver(document.page())
+DeviceSensorEventController::DeviceSensorEventController(Page* page)
+    : PageLifecycleObserver(page)
     , m_hasEventListener(false)
-    , m_document(document)
     , m_isActive(false)
     , m_needsCheckingNullEvents(true)
     , m_timer(this, &DeviceSensorEventController::fireDeviceEvent)
 {
 }
 
 DeviceSensorEventController::~DeviceSensorEventController()
 {
 }
 
 void DeviceSensorEventController::fireDeviceEvent(Timer<DeviceSensorEventController>* timer)
 {
     ASSERT_UNUSED(timer, timer == &m_timer);
     ASSERT(hasLastData());
 
     m_timer.stop();
     dispatchDeviceEvent(getLastEvent());
 }
 
 void DeviceSensorEventController::dispatchDeviceEvent(PassRefPtrWillBeRawPtr<Event> prpEvent)
 {
-    if (!m_document.domWindow() || m_document.activeDOMObjectsAreSuspended() || m_document.activeDOMObjectsAreStopped())
+    Document* targetDocument = document();
+
+    if (!targetDocument || !targetDocument->domWindow() || targetDocument->activeDOMObjectsAreSuspended() || targetDocument->activeDOMObjectsAreStopped())
         return;
 
     RefPtrWillBeRawPtr<Event> event = prpEvent;
-    m_document.domWindow()->dispatchEvent(event);
+    targetDocument->domWindow()->dispatchEvent(event);
 
     if (m_needsCheckingNullEvents) {
         if (isNullEvent(event.get()))
             stopUpdating();
         else
             m_needsCheckingNullEvents = false;
     }
 }
 
 void DeviceSensorEventController::startUpdating()
@@ skipping 27 matching lines @@
     if (!m_hasEventListener)
         return;
 
     if (page()->visibilityState() == PageVisibilityStateVisible)
         startUpdating();
     else
         stopUpdating();
 }
 
 } // namespace WebCore