Revert of Merge apps/pref* to extensions/browser/pref*

Revert of Merge apps/pref* to extensions/browser/pref* (patchset #1 of https://codereview.chromium.org/493003002/)

Reason for revert:
Breaks GN:

http://build.chromium.org/p/chromium.linux/builders/Linux%20GN/builds/10608

Original issue's description:
> Merge apps/pref* to extensions/browser/pref*
> 
> The pref's exclusive user AppWindow will move to extensions/browser
> 
> Merge apps/pref_names.{cc,h} to extensions/browser/pref_names.{cc,h}
> Merge apps/prefs.{cc,h} to extensions/browser/extension_prefs.cc
> 
> BUG=403726
> TBR=bartfab@chromium.org for include fix in configuration_policy_handler_list_factory.cc.
> 
> Committed: https://chromium.googlesource.com/chromium/src/+/3da4417c5baa6b8fe0be9aa012f0fd3294d9dbc7

TBR=benwells@chromium.org,bauerb@chromium.org,bartfab@chromium.org,hashimoto@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=403726
Committed: https://crrev.com/6f93ff91cd3dba63a70f2b860a99c34503580fbb
Cr-Commit-Position: refs/heads/master@{#291652}

[Michael Achenbach, 2014-08-25 08:45:27]

Created Revert of Merge apps/pref* to extensions/browser/pref*

[commit-bot: I haz the power, 2014-08-25 08:46:33]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/machenbach@chromium.org/499253002/1

[commit-bot: I haz the power, 2014-08-25 08:47:13]

Committed patchset #1 (1) as acf084eb2df3b50cdf36a39f6fd01e30f9f82e6f

[commit-bot: I haz the power, 2014-09-10 02:33:26]

Patchset 1 (id:??) landed as
https://crrev.com/6f93ff91cd3dba63a70f2b860a99c34503580fbb
Cr-Commit-Position: refs/heads/master@{#291652}