I just added the google-play-services-lib library to my project and am stuck where I need to \"sync the project with gradle files\", but this button does not exist
google-play-services-lib
In my Case, One of My plugin, Android support got disabled due to some reason , As soon as I enabled it , and sync it the button automatically showed.
Go to File > Settings > Plugin > Android support(Tick this).
and sync your project.