sample service that wrap the google client API

gistfile1.txt

<script src="https://apis.google.com/js/client.js?onload=init"></script>

var init = function() {
  window.initGapi();
}

angular.module('MyModule', [])
.service('gapiService', function($q,$rootScope, $window) {
  var service = $rootScope.$new(true);
  var youtubeAPIready = $q.defer();

  console.log('Create initiGapi method');
  $window.initGapi = function() {
    service.initGapi();
  }
  service.initGapi = function() {
    gapi.client.setApiKey('THEKEY');
    gapi.client.load('youtube', 'v3', function() {
      service.$apply(youtubeAPIready.resolve());
    });
  }

  service.getActivities = function () {
    var that = this;
    var deferred = $q.defer();
    youtubeAPIready.promise.then(function () {
        request = gapi.client.youtube.activities.list({
            part: 'snippet,contentDetails',
            channelId: 'UChYheBnVeCfhCmqZfCUdJQw',
        });

        request.execute(function (data) {
          deferred.resolve(data);
        }, function (response) {
          deferred.reject(response);
        });
    });

    return deferred.promise;
  }

  return service;
});