don’t open a new thread for the same problem, it just isn’t necessary!
you already asked the same thing here: How to use TypeScript definitions @types in ionic2 project
read http://ionicframework.com/docs/v2/faq/ to get the idea of typings/@types
note: rc0 uses @types see the changelog: https://github.com/driftyco/ionic/blob/master/CHANGELOG.md#typings
all you have done now is installed typeScript definitions for Google API Client, did you install/add the Google API Client library too?