Move callback and host port args into Start method

Move callback and host port args into Start method.
Both args are not neccecary as state, so they don't need to be in the
constructor.

BUG=461504
Committed: https://crrev.com/712677166ccd38a780ee991e7075f637fe42cd5f
Cr-Commit-Position: refs/heads/master@{#318146}

[Vitaly Buka (NO REVIEWS), 2015-02-25 02:10:02]

vitalybuka@chromium.org changed reviewers:
+ alekseys@chromium.org

[Vitaly Buka (NO REVIEWS), 2015-02-25 07:26:33]

Patchset #3 (id:40001) has been deleted

[Aleksey Shlyapnikov, 2015-02-25 17:18:13]

lgtm

[Vitaly Buka (NO REVIEWS), 2015-02-25 19:15:38]

The CQ bit was checked by vitalybuka@chromium.org

[commit-bot: I haz the power, 2015-02-25 19:16:32]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/948413006/80001

[commit-bot: I haz the power, 2015-02-25 21:09:23]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-02-25 21:09:24]

Try jobs failed on following builders:
  mac_chromium_rel_ng on tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_rel_...)

[Vitaly Buka (NO REVIEWS), 2015-02-25 22:29:05]

The CQ bit was checked by vitalybuka@chromium.org

[Vitaly Buka (NO REVIEWS), 2015-02-25 22:29:05]

The patchset sent to the CQ was uploaded after l-g-t-m from
alekseys@chromium.org
Link to the patchset: https://codereview.chromium.org/948413006/#ps100001
(title: " ")

[commit-bot: I haz the power, 2015-02-25 22:30:05]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/948413006/100001

[commit-bot: I haz the power, 2015-02-25 23:34:06]

Committed patchset #5 (id:100001)

[commit-bot: I haz the power, 2015-02-25 23:34:44]

Patchset 5 (id:??) landed as
https://crrev.com/712677166ccd38a780ee991e7075f637fe42cd5f
Cr-Commit-Position: refs/heads/master@{#318146}