Extensions: Remove PermissionMessage (permission_message.h/cc)

Extensions: Remove PermissionMessage (permission_message.h/cc)
and all the (unused) code that referenced it.

[This is part 5 of operation "remove the old permission message system".]

BUG=398257
Committed: https://crrev.com/399178470b3d78bb383cdc56d8a3af6474174271
Cr-Commit-Position: refs/heads/master@{#344495}

[Marc Treib, 2015-07-22 11:19:59]

treib@chromium.org changed reviewers:
+ rdevlin.cronin@chromium.org

[Marc Treib, 2015-07-22 11:20:00]

This is the final part of the removals, and the long-awaited conclusion to the
epic saga! :)

[Marc Treib, 2015-07-31 10:05:23]

On 2015/07/22 11:20:00, Marc Treib wrote:
> This is the final part of the removals, and the long-awaited conclusion to the
> epic saga! :)

Ping :)

[Devlin, 2015-07-31 20:03:41]

lgtm if the bots are happy! :)

[Marc Treib, 2015-08-20 12:35:46]

The CQ bit was checked by treib@chromium.org

[Marc Treib, 2015-08-20 12:35:46]

The patchset sent to the CQ was uploaded after l-g-t-m from
rdevlin.cronin@chromium.org
Link to the patchset: https://codereview.chromium.org/1213623006/#ps40001
(title: "fix app_shell build, rebase")

[commit-bot: I haz the power, 2015-08-20 12:36:08]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1213623006/40001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1213623006/40001

[commit-bot: I haz the power, 2015-08-20 13:32:06]

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

[commit-bot: I haz the power, 2015-08-20 13:32:07]

Try jobs failed on following builders:
  win_chromium_rel_ng on tryserver.chromium.win (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_rel_...)

[Marc Treib, 2015-08-20 13:40:57]

The CQ bit was checked by treib@chromium.org

[commit-bot: I haz the power, 2015-08-20 13:41:28]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1213623006/40001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1213623006/40001

[commit-bot: I haz the power, 2015-08-20 14:27:27]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2015-08-20 14:28:19]

Patchset 3 (id:??) landed as
https://crrev.com/399178470b3d78bb383cdc56d8a3af6474174271
Cr-Commit-Position: refs/heads/master@{#344495}