Ive got a @gmail / @googlemail email account that i also use for google drive, google calendar etc.. I would like to update / transfer my google account username to a custom domain eg. sam@mysite.com instead of sam@gmail.com. I would still like to keep my @gmail email address, but not use it as the username i use to login to google drive / calendar etc. Is this possible ? If so how would i do it ? 
Transfer google drive / calendar username from @gmail to a custom domain eg. @mysite.com
google drive;google apps;google calendar