getToken method
Return a token that allows the authorized entity to access the service
defined by scope.
getTokenParams Parameters for getToken.
returns Function called when the retrieval completes. It should check
runtime.lastError for error when token is empty.
Implementation
Future<String> getToken(GetTokenParams getTokenParams) async {
var $res = await promiseToFuture<String>(
$js.chrome.instanceId.getToken(getTokenParams.toJS));
return $res;
}