Blink side of exposing the service worker registration associated with geofencing API calls.

Source/modules/geofencing/Geofencing.h

Index: Source/modules/geofencing/Geofencing.h
diff --git a/Source/modules/geofencing/Geofencing.h b/Source/modules/geofencing/Geofencing.h
index 6624dac90592d5775d79ec4a80c46a9bb745cedb..8de90e76b95c6f27f9b5a69adb66bb73707d976e 100644
--- a/Source/modules/geofencing/Geofencing.h
+++ b/Source/modules/geofencing/Geofencing.h
@@ -15,23 +15,26 @@ class ExecutionContext;
 class GeofencingRegion;
 class ScriptPromise;
 class ScriptState;
+class ServiceWorkerRegistration;
 
 class Geofencing final : public GarbageCollected<Geofencing>, public ScriptWrappable {
     DEFINE_WRAPPERTYPEINFO();
 public:
-    static Geofencing* create()
+    static Geofencing* create(ServiceWorkerRegistration* registration)
     {
-        return new Geofencing();
+        return new Geofencing(registration);
     }
 
     ScriptPromise registerRegion(ScriptState*, GeofencingRegion*);
     ScriptPromise unregisterRegion(ScriptState*, const String& regionId);
     ScriptPromise getRegisteredRegions(ScriptState*) const;
 
-    virtual void trace(Visitor*) { }
+    virtual void trace(Visitor*);
 
 private:
-    Geofencing();
+    explicit Geofencing(ServiceWorkerRegistration*);
+
+    Member<ServiceWorkerRegistration> m_registration;
 };
 
 } // namespace blink