Add page visibility observer support for Device Motion

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 12 matching lines @@
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include "config.h"
 #include "modules/device_orientation/DeviceMotionController.h"
 
 #include "RuntimeEnabledFeatures.h"
 #include "core/dom/Document.h"
 #include "core/dom/EventNames.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)
     : DOMWindowLifecycleObserver(document->domWindow())
     , DeviceSensorEventController(document)
+    , PageLifecycleObserver(document->page())
+    , m_hasEventListener(false)
 {
 }
 
 DeviceMotionController::~DeviceMotionController()
 {
 }
 
 void DeviceMotionController::didChangeDeviceMotion(DeviceMotionData* deviceMotionData)
 {
     dispatchDeviceEvent(DeviceMotionEvent::create(eventNames().devicemotionEvent, deviceMotionData));
@@ skipping 36 matching lines @@
 
 bool DeviceMotionController::isNullEvent(Event* event)
 {
     ASSERT(event->type() == eventNames().devicemotionEvent);
     DeviceMotionEvent* motionEvent = static_cast<DeviceMotionEvent*>(event);
     return !motionEvent->deviceMotionData()->canProvideEventData();
 }
 
 void DeviceMotionController::didAddEventListener(DOMWindow*, const AtomicString& eventType)
 {
-    if (eventType == eventNames().devicemotionEvent && RuntimeEnabledFeatures::deviceMotionEnabled())
-        startUpdating();
+    if (eventType == eventNames().devicemotionEvent && RuntimeEnabledFeatures::deviceMotionEnabled()) {
+        if (page() && page()->visibilityState() == PageVisibilityStateVisible)
+            startUpdating();
+        m_hasEventListener = true;
+    }
 }
 
 void DeviceMotionController::didRemoveEventListener(DOMWindow*, const AtomicString& eventType)
 {
-    if (eventType == eventNames().devicemotionEvent)
+    if (eventType == eventNames().devicemotionEvent) {
         stopUpdating();
+        m_hasEventListener = false;
+    }
 }
 
 void DeviceMotionController::didRemoveAllEventListeners(DOMWindow*)
 {
     stopUpdating();
+    m_hasEventListener = false;
+}
+
+void DeviceMotionController::pageVisibilityChanged()
+{
+    if (!m_hasEventListener)
+        return;
+
+    if (page()->visibilityState() == PageVisibilityStateVisible)
+        startUpdating();
+    else
+        stopUpdating();
 }
 
 } // namespace WebCore