Gracefully support Navigator Gamepad methods in a detached state.

Source/core/frame/DeviceSensorEventController.cpp

Index: Source/core/frame/DeviceSensorEventController.cpp
diff --git a/Source/core/frame/DeviceSensorEventController.cpp b/Source/core/frame/DeviceSensorEventController.cpp
index 912ce1dce9132ba46fd75bf64af4553ec79f4b19..465c15eb9d4b2b21c5bbb1b47630480d08f32349 100644
--- a/Source/core/frame/DeviceSensorEventController.cpp
+++ b/Source/core/frame/DeviceSensorEventController.cpp
@@ -33,8 +33,8 @@
 
 namespace WebCore {
 
-DeviceSensorEventController::DeviceSensorEventController(Document& document)
-    : PageLifecycleObserver(document.page())
+DeviceSensorEventController::DeviceSensorEventController(Document* document)
+    : PageLifecycleObserver(document ? document->page() : 0)

[abarth-chromium, 2014/04/28 17:58:14]

Folks would then class in the Page* rather than the document.

     , m_hasEventListener(false)
     , m_document(document)
     , m_isActive(false)
@@ -58,11 +58,11 @@ void DeviceSensorEventController::fireDeviceEvent(Timer<DeviceSensorEventControl
 
 void DeviceSensorEventController::dispatchDeviceEvent(PassRefPtrWillBeRawPtr<Event> prpEvent)
 {
-    if (!m_document.domWindow() || m_document.activeDOMObjectsAreSuspended() || m_document.activeDOMObjectsAreStopped())
+    if (!m_document || !m_document->domWindow() || m_document->activeDOMObjectsAreSuspended() || m_document->activeDOMObjectsAreStopped())
         return;
 
     RefPtrWillBeRawPtr<Event> event = prpEvent;
-    m_document.domWindow()->dispatchEvent(event);
+    m_document->domWindow()->dispatchEvent(event);
 
     if (m_needsCheckingNullEvents) {
         if (isNullEvent(event.get()))