mus: Remove some dead code from client-lib.

mus: Remove some dead code from client-lib.

|change_acked_callback_| isn't set or used by anything. So remove it.

BUG=none
R=sky@chromium.org

Committed: https://crrev.com/f1054fd66bd7c2e7fafdf4f6e84b582ba4adb983
Cr-Commit-Position: refs/heads/master@{#362898}

[sky, 2015-12-03 03:17:03]

LGTM

[sadrul, 2015-12-03 03:45:25]

The CQ bit was checked by sadrul@chromium.org

[commit-bot: I haz the power, 2015-12-03 03:45:49]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1492183002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1492183002/1

[commit-bot: I haz the power, 2015-12-03 03:52:42]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-12-03 03:53:44]

Description was changed from

==========
mus: Remove some dead code from client-lib.

|change_acked_callback_| isn't set or used by anything. So remove it.

BUG=none
R=sky@chromium.org
==========

to

==========
mus: Remove some dead code from client-lib.

|change_acked_callback_| isn't set or used by anything. So remove it.

BUG=none
R=sky@chromium.org

Committed: https://crrev.com/f1054fd66bd7c2e7fafdf4f6e84b582ba4adb983
Cr-Commit-Position: refs/heads/master@{#362898}
==========

[commit-bot: I haz the power, 2015-12-03 03:53:45]

Patchset 1 (id:??) landed as
https://crrev.com/f1054fd66bd7c2e7fafdf4f6e84b582ba4adb983
Cr-Commit-Position: refs/heads/master@{#362898}