pubsub: match retry code with Java handwritten client (#285)
pubsub: match retry code with Java handwritten client (#285)

* pubsub: match retry code with Java handwritten client

Fixes #284.

* s/poll/pull/

fuchsia-mirror/third_party-googleapis,googleapis/googleapis,garrettjonesgoogle/googleapis,pongad/googleapis,ethanbao/googleapis,googleapis/googleapis,landrito/googleapis,shinfan/googleapis