Access Youtube Channel ID once signed in though Firebase GoogleAuthProvider - firebase-authentication

Question

I've setup a basic Firebase authentication app which uses Google. I've passed the following scopes:
https://www.googleapis.com/auth/youtube.force-ssl
When logging in, it states that it is gaining permission to manage my Youtube Account, but the response I get back has nothing relevant to Youtube in it, such as a channelId.
Even when doing a simple $http.get request against the logged in accounts Youtube subscriptions I get the following response:
The request uses the <code>mine</code> parameter but is not properly authorized.
So would I need to login through Google, then authenticate again once signed in to access my Youtube account?
Sample login:
var provider = new firebase.auth.GoogleAuthProvider();
provider.addScope("https://www.googleapis.com/auth/youtube.force-ssl");
$scope.login = function () {
Auth.$signInWithPopup(provider).then(function (result) {
console.log(result);
console.log("Signed in as:", result.user.uid);
}).catch(function (error) {
console.error("Authentication failed:", error);
});
}

Answer 1

Apologies in the delay.
Here is how I solved this problem. When logging in using Firebase with Google as a provider, I get the access_token given by Google and query YouTubes API to get the correct channel.
An example of my login function is below:
this.loginMainGoogle = function (event) {
gapi.auth2.getAuthInstance().signIn().then(function _firebaseSignIn(googleUser) {
var unsubscribe = $rootScope.authObj.$onAuthStateChanged(function (firebaseUser) {
unsubscribe();
// Check if we are already signed-in Firebase with the correct user.
if (!_isUserEqual(googleUser, firebaseUser)) {
// Build Firebase credential with the Google ID token.
console.log(googleUser.getAuthResponse());
var credential = firebase.auth.GoogleAuthProvider.credential(
googleUser.getAuthResponse().id_token);
// Sign in with credential from the Google user.
return $rootScope.authObj.$signInWithCredential(credential)
.then(function (result) {
var ytToken = googleUser.getAuthResponse().access_token;
localStorage.setItem('gToken', ytToken);
$rootScope.tokenerino = ytToken;
$http.get("https://www.googleapis.com/youtube/v3/channels?part=id&mine=true&access_token=" + ytToken)
.then(function(response) {
$rootScope.myChan = response.data.items[0].id;
localStorage.setItem('myChannelId', $rootScope.myChan);
updateYTChannel(result.uid, response.data.items[0].id);
});
$rootScope.currentLoginStatus = true;
$rootScope.notification("You Have Signed In");
//Don't redirect them if they login via a YouTube playlist
if ($location.path().indexOf('playlists') !== 1) {
$state.go('mymusic');
}
}, function errorCallback(error) {
console.log(error);
});
}
})
});
}
I store the Channel for the user in Firebase, but you can put it in localStorage if you want. The only problem is that the access_token only lasts for 1 hour. Hopefully this helps anyone and if a better solution has been found - feel free to share!