title: queryPurchases() vs queryPurchaseHistoryAsync() in order to 'restore' functionality?
body: <p>I'm using the Play Billing Library in order to trigger and manage purchases which in turn unlocked extra functionality within an app. This part is working. </p>
  
  <p>However, what is the best way to 'restore' purchases. Say for example someone who has bought the app buys a new phone. Logs in to the Play Store, downloads my app and then finds that the payment screen to 'upgrade' is being displayed. iOS has a specific method for this but I'm not aware of one for Android.</p>
  
  <p>My thoughts are to query the Play Store and confirm whether the account has previously SUCCESSFULLY purchased the item, if so then I will call the local upgrade function within the app. </p>
  
  <p>It appears there are two similar methods. But which one should I used in this scenario? Where a user has either wiped their phone or bought a new one?</p>
  
  <p><code>queryPurchases()</code>? Or <code>queryPurchaseHistoryAsync()</code>?</p>