Stop pings when other syncs in the same account start

* When a mailbox syncs, pings should be aborted, or they appear to
  end up timing out with a stale connection (observation from logs)
* The result of timing out is lack of push until the heartbeat time
  has elapsed and our alarm triggers
* Also refactor code; some of the names of methods was unfortunate
  and these methods were being used in this CL

Bug: 2492848
Change-Id: Ib626a5d3cf6d2c61e3b11f4886a3fedbf9727bfa
5 files changed