Code review comment for lp:~niemeyer/juju-core/mstate-machine-watcher

Reviewers: mp+123614_code.launchpad.net,

Message:
Please take a look.

Description:
mstate: add machine watcher

This is the first high-level watcher after the foundation for
watcher is in place, so it adds a few missing pieces onto the
state logic itself too.

https://code.launchpad.net/~niemeyer/juju-core/mstate-machine-watcher/+merge/123614

Requires:
https://code.launchpad.net/~niemeyer/juju-core/mstate-watcher-helpers/+merge/123596

(do not edit description out of merge proposal)

Please review this at https://codereview.appspot.com/6489104/

Affected files:
   A [revision details]
   M mstate/export_test.go
   M mstate/machine.go
   M mstate/machine_test.go
   M mstate/open.go
   M mstate/state.go
   M mstate/state_test.go
   A mstate/watcher.go