Add page visibility observer support for Device Motion

Source/modules/device_orientation/DeviceMotionController.h

 /*
  * 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 11 matching lines @@
  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef DeviceMotionController_h
 #define DeviceMotionController_h
 
 #include "core/dom/Event.h"
 #include "core/page/DOMWindowLifecycleObserver.h"
+#include "core/page/PageLifecycleObserver.h"
 #include "core/platform/Supplementable.h"
 #include "modules/device_orientation/DeviceSensorEventController.h"
 
 namespace WebCore {
 
 class DeviceMotionData;
 class DOMWindow;
 
-class DeviceMotionController : public DeviceSensorEventController, public Supplement<ScriptExecutionContext>, public DOMWindowLifecycleObserver {
+class DeviceMotionController : public DeviceSensorEventController, public Supplement<ScriptExecutionContext>, public DOMWindowLifecycleObserver, public PageLifecycleObserver {
 
 public:
     virtual ~DeviceMotionController();
 
     static const char* supplementName();
     static DeviceMotionController* from(Document*);
 
     void didChangeDeviceMotion(DeviceMotionData*);
 
-    // Inherited from DOMWindowLifecycleObserver
-    virtual void didAddEventListener(DOMWindow*, const AtomicString&) OVERRIDE;
-    virtual void didRemoveEventListener(DOMWindow*, const AtomicString&) OVERRIDE;
-    virtual void didRemoveAllEventListeners(DOMWindow*) OVERRIDE;
-
 private:
     explicit DeviceMotionController(Document*);
     virtual void registerWithDispatcher() OVERRIDE;
     virtual void unregisterWithDispatcher() OVERRIDE;
 
+    // Inherited from DOMWindowLifecycleObserver.
+    virtual void didAddEventListener(DOMWindow*, const AtomicString&) OVERRIDE;
+    virtual void didRemoveEventListener(DOMWindow*, const AtomicString&) OVERRIDE;
+    virtual void didRemoveAllEventListeners(DOMWindow*) OVERRIDE;
+
+    // Inherited from PageLifecycleObserver.
+    virtual void pageVisibilityChanged() OVERRIDE;
+
     virtual bool hasLastData() OVERRIDE;
     virtual PassRefPtr<Event> getLastEvent() OVERRIDE;
     virtual bool isNullEvent(Event*) OVERRIDE;
+
+    bool m_hasEventListener;
 };
 
 } // namespace WebCore
 
 #endif // DeviceMotionController_h