We are being asked to set the OAuth redirect URI for Facebook (as shown below) in the instructions to set up Google Firebase to use Facebook login.
We clicked in every menu for our app. Where is it? Could it be called something different?
From the Firebase documentation:
...make sure your OAuth redirect URI (e.g. my-app-12345.firebaseapp.com/__/auth/handler) is listed as one of your OAuth redirect URIs in your Facebook app's settings page on the Facebook for Developers site in the Product Settings > Facebook Login config.
I had a hard time finding this setting too.
If you are on https://developers.facebook.com/, you can find your apps listed in the top right, next to you profile picture. Selecting the app, will take you to the settings for that app.
In your app settings on https://developers.facebook.com/sa/apps/<my-app-id>, make sure that you add the Facebook Login product. Then under "Client OAuth Settings" enter the URL in the "Valid OAuth redirect URIs" box.
According to new changes in the facebook developers website UI,You can find it over here.Giving an image by image steps to find it.
1.Click on the Add product as in the image below.
2.You get a screen like this.In that you will see a list of products Facebook provides.In the image you can't see facebook login because I have already added it.
3.Click on settings of Facebook login.
4.You will get the required screen showing Client OAuth Login and the field for entering the redirect URL.
1- Go to your Firebase Console -> Authentication -> SIGN-IN METHOD -> Facebook. You'll find that link below your App Secret and App ID. Copy it. (It should be something like this: https://your-app-id.firebaseapp.com/__/auth/handler)
2- Go to https://developers.facebook.com/apps/ -> your app -> Product -> Facebook Login (add it if didn't yet) -> Settings. Past the link you've copied into "Valid OAuth redirect URIs" box.
Its not there in settings anymore. You can find an option "+ Add Product" in the left menu. Select that & then select "Facebook link". There you'll find a box to paste the link.
BTW, this can change whenever FB decides to redesign their Menu UI
look left bar, under the PRODUCTS title, and double click facebook Login title.
来源：https://stackoverflow.com/questions/37449761/where-does-one-set-the-oauth-redirect-uri-for-facebook-apps