[Background Sync] Add sync registration details to onsync event

Source/modules/background_sync/SyncRegistration.h

Index: Source/modules/background_sync/SyncRegistration.h
diff --git a/Source/modules/background_sync/SyncRegistration.h b/Source/modules/background_sync/SyncRegistration.h
index 838b029ec408d96d3d76fbec78b4ae1d8e12fcb3..65c27517b93ea37994bacd755f24b1a9d56c2a9b 100644
--- a/Source/modules/background_sync/SyncRegistration.h
+++ b/Source/modules/background_sync/SyncRegistration.h
@@ -18,9 +18,10 @@ class ScriptPromiseResolver;
 class ScriptState;
 struct WebSyncRegistration;
 
-class SyncRegistration final : public GarbageCollectedFinalized<SyncRegistration>, public ScriptWrappable {
+class MODULES_EXPORT SyncRegistration final : public GarbageCollectedFinalized<SyncRegistration>, public ScriptWrappable {
     DEFINE_WRAPPERTYPEINFO();
 public:
+    static SyncRegistration* create(const WebSyncRegistration&, ServiceWorkerRegistration*);
     static SyncRegistration* take(ScriptPromiseResolver*, WebSyncRegistration*, ServiceWorkerRegistration*);
     static void dispose(WebSyncRegistration* registrationRaw);