Stop firing orientationchange events at pages that are not visible

Source/core/dom/FullscreenElementStack.h

Index: Source/core/dom/FullscreenElementStack.h
diff --git a/Source/core/dom/FullscreenElementStack.h b/Source/core/dom/FullscreenElementStack.h
index 9fd69454726e606b04240c87a9e97add06ab51f0..964787ceecf244872a0e074e44807dae60c49aba 100644
--- a/Source/core/dom/FullscreenElementStack.h
+++ b/Source/core/dom/FullscreenElementStack.h
@@ -41,10 +41,11 @@ namespace WebCore {
 
 class Document;
 class Element;
+class ExecutionContext;
+class FullscreenObserver;
 class Node;
 class RenderFullScreen;
 class RenderStyle;
-class ExecutionContext;
 
 class FullscreenElementStack FINAL
     : public NoBaseWillBeGarbageCollectedFinalized<FullscreenElementStack>
@@ -101,6 +102,9 @@ public:
 
     virtual void trace(Visitor*) OVERRIDE;
 
+    void addObserver(FullscreenObserver*);
+    void removeObserver(FullscreenObserver*);
+
 private:
     static FullscreenElementStack* fromIfExistsSlow(Document&);
 
@@ -109,6 +113,8 @@ private:
     Document* document();
     void fullScreenChangeDelayTimerFired(Timer<FullscreenElementStack>*);
 
+    void notifyObserversDidFullyExitFullScreen();
+
     bool m_areKeysEnabledInFullScreen;
     RefPtrWillBeMember<Element> m_fullScreenElement;
     WillBeHeapVector<RefPtrWillBeMember<Element> > m_fullScreenElementStack;
@@ -118,6 +124,8 @@ private:
     WillBeHeapDeque<RefPtrWillBeMember<Node> > m_fullScreenErrorEventTargetQueue;
     LayoutRect m_savedPlaceholderFrameRect;
     RefPtr<RenderStyle> m_savedPlaceholderRenderStyle;
+    typedef HashSet<FullscreenObserver*> FullscreenObserverSet;
+    FullscreenObserverSet m_fullscreenObservers;
 };
 
 inline bool FullscreenElementStack::isActiveFullScreenElement(const Element* element)