Last September I recommended use of a Chrome Extension called Google+Tweet on this blog.
I no longer recommend this. Google+Tweet has recently become a source of annoying and hard to remove adware called dropinsavings$ which pops up over various websites. For more information see one of the replies to this thread:
how to delete "drop in savings" bug ...keeps dropping down each web site where I am trying to buy something. - Google Groups:
'via Blog this'