Gracefully support Navigator Gamepad methods in a detached state.

Source/modules/device_orientation/DeviceMotionController.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 19 matching lines @@
 #include "core/dom/Document.h"
 #include "core/frame/DOMWindow.h"
 #include "core/page/Page.h"
 #include "modules/device_orientation/DeviceMotionData.h"
 #include "modules/device_orientation/DeviceMotionDispatcher.h"
 #include "modules/device_orientation/DeviceMotionEvent.h"
 
 namespace WebCore {
 
 DeviceMotionController::DeviceMotionController(Document& document)
-    : DeviceSensorEventController(document)
+    : DeviceSensorEventController(document.page())
     , DOMWindowLifecycleObserver(document.domWindow())
+    , m_document(document)
 {
 }
 
 DeviceMotionController::~DeviceMotionController()
 {
     stopUpdating();
 }
 
 void DeviceMotionController::didChangeDeviceMotion(DeviceMotionData* deviceMotionData)
 {
@@ skipping 34 matching lines @@
 {
     DeviceMotionDispatcher::instance().removeDeviceMotionController(this);
 }
 
 bool DeviceMotionController::isNullEvent(Event* event)
 {
     DeviceMotionEvent* motionEvent = toDeviceMotionEvent(event);
     return !motionEvent->deviceMotionData()->canProvideEventData();
 }
 
+Document* DeviceMotionController::document()
+{
+    return &m_document;
+}
+
 void DeviceMotionController::didAddEventListener(DOMWindow* window, const AtomicString& eventType)
 {
     if (eventType != EventTypeNames::devicemotion)
         return;
 
     if (page() && page()->visibilityState() == PageVisibilityStateVisible)
         startUpdating();
 
     m_hasEventListener = true;
 }
 
 void DeviceMotionController::didRemoveEventListener(DOMWindow* window, const AtomicString& eventType)
 {
     if (eventType != EventTypeNames::devicemotion || window->hasEventListeners(EventTypeNames::devicemotion))
         return;
 
     stopUpdating();
     m_hasEventListener = false;
 }
 
 void DeviceMotionController::didRemoveAllEventListeners(DOMWindow*)
 {
     stopUpdating();
     m_hasEventListener = false;
 }
 
 } // namespace WebCore