use get_string_literal() in provider arg parsing
use get_string_literal() in provider arg parsing

Reviewed By: mofeiZ

Differential Revision: D34154563

fbshipit-source-id: a490a1652238cb90d3b690541e0d3402fc8fa361

xuorig/relay,kassens/relay,kassens/relay,voideanvalue/relay,josephsavona/relay,voideanvalue/relay,xuorig/relay,voideanvalue/relay,kassens/relay,wincent/relay,wincent/relay,xuorig/relay,facebook/relay,facebook/relay,voideanvalue/relay,wincent/relay,kassens/relay,voideanvalue/relay,facebook/relay,facebook/relay,josephsavona/relay,facebook/relay,wincent/relay,xuorig/relay,facebook/relay,josephsavona/relay,xuorig/relay,kassens/relay,wincent/relay,wincent/relay,voideanvalue/relay,xuorig/relay,kassens/relay