Make ScreenOrientationController a FrameDestructionObserver.

Source/modules/screen_orientation/ScreenOrientationController.h

Index: Source/modules/screen_orientation/ScreenOrientationController.h
diff --git a/Source/modules/screen_orientation/ScreenOrientationController.h b/Source/modules/screen_orientation/ScreenOrientationController.h
index b4d323ed6928cb1c533f6ff45d669813cb3b230a..0693296f21a15f6c8c39f61139a037cfb05945cd 100644
--- a/Source/modules/screen_orientation/ScreenOrientationController.h
+++ b/Source/modules/screen_orientation/ScreenOrientationController.h
@@ -5,6 +5,7 @@
 #ifndef ScreenOrientationController_h
 #define ScreenOrientationController_h
 
+#include "core/frame/FrameDestructionObserver.h"
 #include "core/frame/PlatformEventController.h"
 #include "platform/Supplementable.h"
 #include "platform/Timer.h"
@@ -21,6 +22,7 @@ class WebScreenOrientationClient;
 class ScreenOrientationController FINAL
     : public NoBaseWillBeGarbageCollectedFinalized<ScreenOrientationController>
     , public WillBeHeapSupplement<LocalFrame>
+    , public FrameDestructionObserver
     , public PlatformEventController {
     WILL_BE_USING_GARBAGE_COLLECTED_MIXIN(ScreenOrientationController);
     WTF_MAKE_NONCOPYABLE(ScreenOrientationController);
@@ -33,13 +35,11 @@ public:
     void lock(WebScreenOrientationLockType, WebLockOrientationCallback*);
     void unlock();
 
-    const LocalFrame& frame() const;
-
     static void provideTo(LocalFrame&, WebScreenOrientationClient*);
     static ScreenOrientationController* from(LocalFrame&);
     static const char* supplementName();
 
-    virtual void trace(Visitor*);
+    virtual void trace(Visitor*) OVERRIDE;
 
 private:
     explicit ScreenOrientationController(LocalFrame&, WebScreenOrientationClient*);
@@ -58,9 +58,10 @@ private:
 
     void dispatchEventTimerFired(Timer<ScreenOrientationController>*);
 
+    bool isActiveAndVisible() const;
+
     PersistentWillBeMember<ScreenOrientation> m_orientation;
     WebScreenOrientationClient* m_client;
-    LocalFrame& m_frame;
     Timer<ScreenOrientationController> m_dispatchEventTimer;
 };