Persistent Storage

I use Inexed-DB in ionic3 application in some cases, some IDB nodes are deleted by the userAgent. in MDN, i found a method navigator.storage , that persists the storage and prevents the userAgent from deleting in case of storage pressure

I try to run this in my ionic 3 code like:

declare var navigator;
navigator.storage.persist().then(function(persistent) {
      if (persistent)
        console.log("true");
      else
        console.log("false");
    });

but i got always

false

Is ther any way to persist it (such as permissions or any thing else)

these links may help:
Chrome Persistnet storage

StorageManager.persist() Reference